feat(05-01): enrich BACKEND_REGISTRY and update all consumers

- Change BACKEND_REGISTRY shape from Record<BackendType, FieldDef[]> to
  Record<BackendType, { displayName, description, fields: FieldDef[] }>
- Add displayName and description to azureblob, s3, s3-compatible entries
- Update schemas/index.ts buildZodSchema to use .fields access
- Update RemoteConfigStep.tsx two .fields accesses (azureblob.find + map)

src/components/wizard/RemoteConfigStep.tsx

@@ -55,7 +55,7 @@ export function RemoteConfigStep() {
           <>
             {/* Account field via FieldRenderer */}
             <FieldRenderer
-              field={BACKEND_REGISTRY.azureblob.find(f => f.key === 'account')!}
+              field={BACKEND_REGISTRY.azureblob.fields.find(f => f.key === 'account')!}
               register={register}
               error={errors.account as FieldError | undefined}
             />
@@ -70,7 +70,7 @@ export function RemoteConfigStep() {
           </>
         ) : (
           /* S3 and S3-compatible: full registry loop — FieldRenderer handles provider hiding */
-          BACKEND_REGISTRY[backendType].map(field => (
+          BACKEND_REGISTRY[backendType].fields.map(field => (
             <FieldRenderer
               key={field.key}
               field={field}

src/schemas/index.ts

@@ -7,7 +7,7 @@ import { z } from 'zod';
 import { BACKEND_REGISTRY, BackendType } from './registry';
 
 function buildZodSchema(backendType: BackendType): z.ZodObject<Record<string, z.ZodTypeAny>> {
-  const fields = BACKEND_REGISTRY[backendType];
+  const fields = BACKEND_REGISTRY[backendType].fields;
   const shape: Record<string, z.ZodTypeAny> = {};
   for (const field of fields) {
     shape[field.key] = field.required

src/schemas/registry.ts

@@ -16,8 +16,15 @@ export interface FieldDef {
   options?: { value: string; label: string }[]; // for inputType: 'select'
 }
 
-export const BACKEND_REGISTRY: Record<BackendType, FieldDef[]> = {
+export const BACKEND_REGISTRY: Record<BackendType, {
-  azureblob: [
+  displayName: string;
+  description: string;
+  fields: FieldDef[];
+}> = {
+  azureblob: {
+    displayName: 'Azure Blob Storage',
+    description: 'Microsoft Azure cloud storage',
+    fields: [
       {
         key: 'account',
         label: 'Storage Account Name',
@@ -42,7 +49,11 @@ export const BACKEND_REGISTRY: Record<BackendType, FieldDef[]> = {
         helpText: 'Full SAS URL including account and container. Provide either this or an access key, not both.',
       },
     ],
-  s3: [
+  },
+  s3: {
+    displayName: 'Amazon S3',
+    description: 'AWS Simple Storage Service',
+    fields: [
       {
         key: 'provider',
         label: 'Provider',
@@ -71,7 +82,11 @@ export const BACKEND_REGISTRY: Record<BackendType, FieldDef[]> = {
         placeholder: 'us-east-1',
       },
     ],
-  's3-compatible': [
+  },
+  's3-compatible': {
+    displayName: 'S3-Compatible',
+    description: 'Wasabi, MinIO, Cloudflare R2, and others',
+    fields: [
       {
         key: 'provider',
         label: 'Provider',
@@ -109,4 +124,5 @@ export const BACKEND_REGISTRY: Record<BackendType, FieldDef[]> = {
         helpText: 'Optional for most S3-compatible providers',
       },
     ],
+  },
 };