Add sidebar app sub-nav with categories, category filter, and re-analysis on category creation

- Sidebar: Apps accordion expands to Documents, which expands to list all
  user categories; clicking a category navigates to /apps/documents?category_id=<id>
- DocumentsPage: reads category_id from URL and applies filter; shows active
  category chip in FilterBar with dismiss; removed TagEditor (deferred)
- doc-service GET /documents: new category_id query param filters via subquery
- doc-service POST /documents/categories: detects similar category names and
  triggers background re-analysis of affected documents so the new category
  surfaces as a pending AI suggestion on relevant docs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

features/doc-service/STATUS.md

@@ -23,7 +23,7 @@ Database: shared PostgreSQL instance, isolated via `alembic_version_doc_service`
 | Method | Path | Description |
 |--------|------|-------------|
 | `POST` | `/documents/upload` | Upload PDF; returns 202 with initial doc row |
-| `GET` | `/documents` | Paginated list with filters and sort |
+| `GET` | `/documents` | Paginated list with filters, sort, and optional `category_id` filter |
 | `GET` | `/documents/{id}` | Single document |
 | `GET` | `/documents/{id}/status` | Lightweight status poll |
 | `GET` | `/documents/{id}/download` | Stream file bytes |
@@ -32,7 +32,9 @@ Database: shared PostgreSQL instance, isolated via `alembic_version_doc_service`
 | `PATCH` | `/documents/{id}/tags` | Replace tag list (dedup, preserve order) |
 | `PATCH` | `/documents/{id}/title` | Update editable title |
 | `GET` | `/documents/categories` | List all categories for the user |
-| `POST` | `/documents/categories` | Create a category |
+| `POST` | `/documents/categories` | Create a category; triggers re-analysis of documents in similar categories |
+| `PATCH` | `/documents/categories/{id}` | Rename a category |
+| `DELETE` | `/documents/categories/{id}` | Delete a category |
 | `POST` | `/documents/{id}/categories/{cat_id}` | Assign category to document |
 | `DELETE` | `/documents/{id}/categories/{cat_id}` | Remove category from document |
 
@@ -49,6 +51,7 @@ Query params:
 | `status` | — | filter by status string |
 | `document_type` | — | filter by document type |
 | `search` | — | case-insensitive ILIKE on `title`, `filename`, `tags`, `document_type` |
+| `category_id` | — | filter to documents assigned to this category UUID |
 
 Response: `{ items: [...], total: N, page: N, pages: N }`