feat(03-02): create FieldRenderer and AzureAuthToggle

- FieldRenderer: registry-driven input renderer (text, password, select, hidden provider)
- AzureAuthToggle: segmented SAS/Key toggle, defaults to SAS, both fields always registered via CSS show/hide
- Both fields preserved on toggle (no conditional rendering that would lose react-hook-form state)

src/components/ui/FieldRenderer.tsx

@@ -0,0 +1,82 @@
+import type { UseFormRegister, FieldError } from 'react-hook-form';
+import type { FieldDef } from '../../schemas/registry';
+import { PasswordField } from './PasswordField';
+
+interface FieldRendererProps {
+  field: FieldDef;
+  register: UseFormRegister<any>;
+  error?: FieldError;
+}
+
+export function FieldRenderer({ field, register, error }: FieldRendererProps) {
+  // provider field: single-option select — hide from UI, auto-register with default value
+  if (field.key === 'provider' && field.options?.length === 1) {
+    return (
+      <input
+        type="hidden"
+        value={field.options[0].value}
+        {...register(field.key)}
+      />
+    );
+  }
+
+  if (field.inputType === 'password') {
+    return (
+      <PasswordField
+        id={field.key}
+        label={field.label}
+        error={error}
+        registration={register(field.key)}
+        placeholder={field.placeholder}
+        helpText={field.helpText}
+      />
+    );
+  }
+
+  if (field.inputType === 'select' && field.options) {
+    return (
+      <div className="flex flex-col gap-1">
+        <label htmlFor={field.key} className="text-sm font-medium text-gray-700">
+          {field.label}
+          {field.required && <span className="ml-1 text-red-500">*</span>}
+        </label>
+        <select
+          id={field.key}
+          className={[
+            'w-full rounded-md border px-3 py-2 text-sm focus:outline-none focus:ring-2',
+            error ? 'border-red-500 focus:ring-red-300' : 'border-gray-300 focus:ring-blue-300',
+          ].join(' ')}
+          {...register(field.key)}
+        >
+          {field.options.map(opt => (
+            <option key={opt.value} value={opt.value}>{opt.label}</option>
+          ))}
+        </select>
+        {field.helpText && !error && <p className="text-xs text-gray-500">{field.helpText}</p>}
+        {error && <p className="text-xs text-red-600">{error.message}</p>}
+      </div>
+    );
+  }
+
+  // text (default)
+  return (
+    <div className="flex flex-col gap-1">
+      <label htmlFor={field.key} className="text-sm font-medium text-gray-700">
+        {field.label}
+        {field.required && <span className="ml-1 text-red-500">*</span>}
+      </label>
+      <input
+        id={field.key}
+        type="text"
+        placeholder={field.placeholder}
+        className={[
+          'w-full rounded-md border px-3 py-2 text-sm focus:outline-none focus:ring-2',
+          error ? 'border-red-500 focus:ring-red-300' : 'border-gray-300 focus:ring-blue-300',
+        ].join(' ')}
+        {...register(field.key)}
+      />
+      {field.helpText && !error && <p className="text-xs text-gray-500">{field.helpText}</p>}
+      {error && <p className="text-xs text-red-600">{error.message}</p>}
+    </div>
+  );
+}

src/components/wizard/AzureAuthToggle.tsx

@@ -0,0 +1,70 @@
+import { useState } from 'react';
+import type { UseFormRegister, FieldError } from 'react-hook-form';
+import { PasswordField } from '../ui/PasswordField';
+
+type AuthMethod = 'sas' | 'key';
+
+interface AzureAuthToggleProps {
+  register: UseFormRegister<any>;
+  errors: {
+    key?: FieldError;
+    sas_url?: FieldError;
+  };
+}
+
+export function AzureAuthToggle({ register, errors }: AzureAuthToggleProps) {
+  const [authMethod, setAuthMethod] = useState<AuthMethod>('sas');
+
+  return (
+    <div className="flex flex-col gap-3">
+      {/* Segmented control */}
+      <div className="flex rounded-md border border-gray-300 overflow-hidden">
+        <button
+          type="button"
+          onClick={() => setAuthMethod('sas')}
+          className={[
+            'flex-1 py-1.5 text-sm font-medium transition-colors',
+            authMethod === 'sas'
+              ? 'bg-blue-600 text-white'
+              : 'bg-white text-gray-700 hover:bg-gray-50',
+          ].join(' ')}
+        >
+          SAS URL
+        </button>
+        <button
+          type="button"
+          onClick={() => setAuthMethod('key')}
+          className={[
+            'flex-1 py-1.5 text-sm font-medium transition-colors',
+            authMethod === 'key'
+              ? 'bg-blue-600 text-white'
+              : 'bg-white text-gray-700 hover:bg-gray-50',
+          ].join(' ')}
+        >
+          Access Key
+        </button>
+      </div>
+
+      {/* Both fields always registered — only active one visible via CSS */}
+      <div className={authMethod === 'sas' ? 'block' : 'hidden'}>
+        <PasswordField
+          id="sas_url"
+          label="SAS URL"
+          error={errors.sas_url}
+          registration={register('sas_url')}
+          placeholder="https://mystorageaccount.blob.core.windows.net/?sv=..."
+          helpText="Full SAS URL including account and container"
+        />
+      </div>
+      <div className={authMethod === 'key' ? 'block' : 'hidden'}>
+        <PasswordField
+          id="key"
+          label="Access Key"
+          error={errors.key}
+          registration={register('key')}
+          helpText="Base64-encoded storage account key"
+        />
+      </div>
+    </div>
+  );
+}