feat(13-04): wire all new backends into RemoteConfigStep

- Replace manual backendLabel record with registry-derived Object.fromEntries
- Import OAuthInstructions and GdriveAuthToggle components
- Refactor 3-branch ternary into renderBackendFields() switch function
- Add gdrive branch: GdriveAuthToggle + generic loop for non-auth fields
- Add onedrive branch: OAuthInstructions + generic loop
- Add dropbox/box/pcloud branches: OAuthInstructions + generic loop
- Default branch covers all other backends (azure-files, swift, ftp, webdav, smb, http, seafile)

src/components/wizard/RemoteConfigStep.tsx

@@ -6,13 +6,185 @@ import { useForm } from 'react-hook-form';
 import { zodResolver } from '@hookform/resolvers/zod';
 import { useWizard } from '../../store/context';
 import { BACKEND_REGISTRY } from '../../schemas/registry';
+import type { BackendType } from '../../schemas/registry';
 import { BACKEND_SCHEMAS } from '../../schemas';
 import { FieldRenderer } from '../ui/FieldRenderer';
 import { AzureAuthToggle } from './AzureAuthToggle';
 import { SftpAuthToggle } from './SftpAuthToggle';
+import { OAuthInstructions } from './OAuthInstructions';
+import { GdriveAuthToggle } from './GdriveAuthToggle';
 import type { FieldError, FieldErrors } from 'react-hook-form';
 import { MD3_BTN_FILLED, MD3_BTN_OUTLINED } from '../../styles/md3-buttons';
 
+// backendLabel derived from registry — no manual duplication
+const backendLabel = Object.fromEntries(
+  Object.entries(BACKEND_REGISTRY).map(([k, v]) => [k, v.displayName])
+) as Record<BackendType, string>;
+
+function renderBackendFields(
+  backendType: BackendType,
+  register: ReturnType<typeof useForm>['register'],
+  errors: Record<string, unknown>
+) {
+  switch (backendType) {
+    case 'azureblob':
+      return (
+        <>
+          {/* Account field via FieldRenderer */}
+          <FieldRenderer
+            field={BACKEND_REGISTRY.azureblob.fields.find(f => f.key === 'account')!}
+            register={register}
+            error={errors.account as FieldError | undefined}
+          />
+          {/* Auth toggle handles key + sas_url — both always registered */}
+          <AzureAuthToggle
+            register={register}
+            errors={{
+              key: errors.key as FieldError | undefined,
+              sas_url: errors.sas_url as FieldError | undefined,
+            }}
+          />
+        </>
+      );
+
+    case 'sftp':
+      return (
+        <>
+          {/* host and user via FieldRenderer */}
+          <FieldRenderer
+            field={BACKEND_REGISTRY.sftp.fields.find(f => f.key === 'host')!}
+            register={register}
+            error={errors.host as FieldError | undefined}
+          />
+          <FieldRenderer
+            field={BACKEND_REGISTRY.sftp.fields.find(f => f.key === 'user')!}
+            register={register}
+            error={errors.user as FieldError | undefined}
+          />
+          {/* Auth toggle handles pass + key_pem — both always registered */}
+          <SftpAuthToggle
+            register={register}
+            errors={{
+              pass: errors.pass as FieldError | undefined,
+              key_pem: errors.key_pem as FieldError | undefined,
+            }}
+          />
+        </>
+      );
+
+    case 'gdrive':
+      return (
+        <>
+          <GdriveAuthToggle
+            register={register}
+            errors={{
+              token: errors.token as FieldError | undefined,
+              service_account_credentials: errors.service_account_credentials as FieldError | undefined,
+            }}
+          />
+          {BACKEND_REGISTRY.gdrive.fields
+            .filter(f => f.key !== 'token' && f.key !== 'service_account_credentials')
+            .map(field => (
+              <FieldRenderer
+                key={field.key}
+                field={field}
+                register={register}
+                error={errors[field.key] as FieldError | undefined}
+              />
+            ))}
+        </>
+      );
+
+    case 'onedrive':
+      return (
+        <>
+          <OAuthInstructions
+            backendName="OneDrive"
+            authorizeCommand='rclone authorize "onedrive"'
+          />
+          {BACKEND_REGISTRY.onedrive.fields.map(field => (
+            <FieldRenderer
+              key={field.key}
+              field={field}
+              register={register}
+              error={errors[field.key] as FieldError | undefined}
+            />
+          ))}
+        </>
+      );
+
+    case 'dropbox':
+      return (
+        <>
+          <OAuthInstructions
+            backendName="Dropbox"
+            authorizeCommand='rclone authorize "dropbox"'
+          />
+          {BACKEND_REGISTRY.dropbox.fields.map(field => (
+            <FieldRenderer
+              key={field.key}
+              field={field}
+              register={register}
+              error={errors[field.key] as FieldError | undefined}
+            />
+          ))}
+        </>
+      );
+
+    case 'box':
+      return (
+        <>
+          <OAuthInstructions
+            backendName="Box"
+            authorizeCommand='rclone authorize "box"'
+          />
+          {BACKEND_REGISTRY.box.fields.map(field => (
+            <FieldRenderer
+              key={field.key}
+              field={field}
+              register={register}
+              error={errors[field.key] as FieldError | undefined}
+            />
+          ))}
+        </>
+      );
+
+    case 'pcloud':
+      return (
+        <>
+          <OAuthInstructions
+            backendName="pCloud"
+            authorizeCommand='rclone authorize "pcloud"'
+          />
+          {BACKEND_REGISTRY.pcloud.fields.map(field => (
+            <FieldRenderer
+              key={field.key}
+              field={field}
+              register={register}
+              error={errors[field.key] as FieldError | undefined}
+            />
+          ))}
+        </>
+      );
+
+    default:
+      // All other backends (azure-files, swift, ftp, webdav, smb, http, seafile, s3, s3-compatible, gcs, b2):
+      // generic FieldRenderer loop driven by registry
+      return (
+        <>
+          {BACKEND_REGISTRY[backendType].fields.map(field => (
+            <FieldRenderer
+              key={field.key}
+              field={field}
+              register={register}
+              error={errors[field.key] as FieldError | undefined}
+            />
+          ))}
+        </>
+      );
+  }
+}
+
 export function RemoteConfigStep() {
   const { state, dispatch } = useWizard();
   const backendType = state.remote.backendType;
@@ -50,16 +222,6 @@ export function RemoteConfigStep() {
     }
   }
 
-  const backendLabel: Record<NonNullable<typeof backendType>, string> = {
-    azureblob:       'Azure Blob Storage',
-    s3:              'Amazon S3',
-    's3-compatible': 'S3-Compatible Storage',
-    onedrive:        'OneDrive',
-    sftp:            'SFTP',
-    gcs:             'Google Cloud Storage',
-    b2:              'Backblaze B2',
-  };
-
   return (
     <div>
       <h2 className="text-2xl font-bold text-on-surface mb-2">Step 2: Configure {backendLabel[backendType]}</h2>
@@ -68,56 +230,7 @@ export function RemoteConfigStep() {
         generated rclone.conf and are never sent to any server.
       </p>
       <form onSubmit={handleSubmit(onNext, onInvalidSubmit)}>
-        {backendType === 'azureblob' ? (
+        {renderBackendFields(backendType, register, errors as Record<string, unknown>)}
-          <>
-            {/* Account field via FieldRenderer */}
-            <FieldRenderer
-              field={BACKEND_REGISTRY.azureblob.fields.find(f => f.key === 'account')!}
-              register={register}
-              error={errors.account as FieldError | undefined}
-            />
-            {/* Auth toggle handles key + sas_url — both always registered */}
-            <AzureAuthToggle
-              register={register}
-              errors={{
-                key: errors.key as FieldError | undefined,
-                sas_url: errors.sas_url as FieldError | undefined,
-              }}
-            />
-          </>
-        ) : backendType === 'sftp' ? (
-          <>
-            {/* host and user via FieldRenderer */}
-            <FieldRenderer
-              field={BACKEND_REGISTRY.sftp.fields.find(f => f.key === 'host')!}
-              register={register}
-              error={errors.host as FieldError | undefined}
-            />
-            <FieldRenderer
-              field={BACKEND_REGISTRY.sftp.fields.find(f => f.key === 'user')!}
-              register={register}
-              error={errors.user as FieldError | undefined}
-            />
-            {/* Auth toggle handles pass + key_pem — both always registered */}
-            <SftpAuthToggle
-              register={register}
-              errors={{
-                pass: errors.pass as FieldError | undefined,
-                key_pem: errors.key_pem as FieldError | undefined,
-              }}
-            />
-          </>
-        ) : (
-          /* All others (onedrive, gcs, b2, s3, s3-compatible): full registry loop */
-          BACKEND_REGISTRY[backendType].fields.map(field => (
-            <FieldRenderer
-              key={field.key}
-              field={field}
-              register={register}
-              error={errors[field.key] as FieldError | undefined}
-            />
-          ))
-        )}
         <div className="flex flex-col sm:flex-row gap-3 mt-6">
           <button
             type="button"