feat(13-01): auto-generate BACKEND_SCHEMAS, update RCLONE_TYPE_MAP for all 18 backends

- BACKEND_SCHEMAS now auto-generated via Object.fromEntries over registry keys
- RCLONE_TYPE_MAP expanded with 11 new entries for all 18 backend types
- RCLONE_TYPE_MAP exported for direct testing
- index.test.ts: added auto-generation coverage (3 tests) + 4 new backend schema smoke tests
- rclone-conf.test.ts: added RCLONE_TYPE_MAP exhaustiveness test + gdrive/ftp/smb conf output tests
- Rule 1 fix: BackendSelectionStep test used /next/i regex matching WebDAV "NextCloud" card buttons

src/schemas/index.ts

@@ -2,6 +2,7 @@
 // Zod schemas derived programmatically from the Backend Schema Registry.
 // DO NOT hand-write z.object() calls with hardcoded field names — all shapes come from the registry.
 // Adding a field to BACKEND_REGISTRY automatically adds it to validation.
+// BACKEND_SCHEMAS is auto-generated from registry keys — no manual per-backend calls needed.
 
 import { z } from 'zod';
 import { BACKEND_REGISTRY, BackendType } from './registry';
@@ -27,13 +28,8 @@ function buildZodSchema(backendType: BackendType): z.ZodObject<Record<string, z.
   return z.object(shape);
 }
 
-export const BACKEND_SCHEMAS = {
-  azureblob:        buildZodSchema('azureblob'),
-  s3:               buildZodSchema('s3'),
-  's3-compatible':  buildZodSchema('s3-compatible'),
-  onedrive:         buildZodSchema('onedrive'),
-  sftp:             buildZodSchema('sftp'),
-  gcs:              buildZodSchema('gcs'),
-  b2:               buildZodSchema('b2'),
-} as const;
-
+// Auto-generated from registry keys — expands automatically when BACKEND_REGISTRY grows.
+// No manual buildZodSchema() call needed per new backend.
+export const BACKEND_SCHEMAS = Object.fromEntries(
+  (Object.keys(BACKEND_REGISTRY) as BackendType[]).map(t => [t, buildZodSchema(t)])
+) as Record<BackendType, ReturnType<typeof buildZodSchema>>;