Add shared file storage with folder tree, permissions, and file manager UI

New document hub for centralized file storage — replaces scattered
drives and USB sticks for non-technical SMBs. Three new tables:
storage_folder (nested hierarchy), storage_folder_permission (role
and user-level access control), storage_file.

Backend: folder CRUD with nested paths, file upload/download via
signed URLs, permission checks (view/edit/admin with inheritance
from parent folders), public/private toggle, breadcrumb navigation,
file search.

Frontend: two-panel file manager — collapsible folder tree on left,
icon grid view on right. Folder icons by type, file size display,
upload button, context menu for download/delete. Breadcrumb nav.
Files sidebar link added.

packages/backend/src/main.ts

@@ -16,6 +16,7 @@ import { lookupRoutes } from './routes/v1/lookups.js'
 import { fileRoutes } from './routes/v1/files.js'
 import { rbacRoutes } from './routes/v1/rbac.js'
 import { repairRoutes } from './routes/v1/repairs.js'
+import { storageRoutes } from './routes/v1/storage.js'
 import { RbacService } from './services/rbac.service.js'
 
 export async function buildApp() {
@@ -67,6 +68,7 @@ export async function buildApp() {
   await app.register(fileRoutes, { prefix: '/v1' })
   await app.register(rbacRoutes, { prefix: '/v1' })
   await app.register(repairRoutes, { prefix: '/v1' })
+  await app.register(storageRoutes, { prefix: '/v1' })
 
   // Auto-seed system permissions on startup
   app.addHook('onReady', async () => {