test(api): add Bruno API collection for saved filters

Add comprehensive Bruno OpenCollection YAML files for testing
the saved filters API with 9 request files and scenarios.

Main CRUD Requests (4 files):
1. List Saved Filters.yml
   - GET /api/saved-filters?resource_type=media-items
   - Documents resource_type parameter requirement
   - Example responses with JSONB filters

2. Create Saved Filter.yml
   - POST /api/saved-filters
   - Complete request body documentation
   - All filter field examples (genre, author, sort, year, etc.)
   - Validation rules (max 100 chars, uniqueness)

3. Update Saved Filter.yml
   - PUT /api/saved-filters/{filter_id}
   - Immutability notes (resource_type can't change)
   - Duplicate name validation
   - Updated timestamp behavior

4. Delete Saved Filter.yml
   - DELETE /api/saved-filters/{filter_id}
   - 204 No Content response
   - Security considerations

Scenario Test Files (5 files):

1. Duplicate Name Validation.yml
   - Tests 409 Conflict on duplicate names
   - Per-user + per-resource-type uniqueness
   - Example bash test script

2. User Isolation - Cross-User Access.yml
   - Tests users can't access each other's filters
   - Security: 404 instead of 403 (prevents enumeration)
   - Complete multi-user test scenario
   - Database-level isolation documentation

3. Multiple Resource Types.yml
   - Tests generic design with different resource types
   - Same name allowed for different types (media-items, collections, devices)
   - Examples for each resource type
   - Extensibility benefits explained

4. Complete CRUD Workflow.yml
   - End-to-end lifecycle test (6.5K file)
   - Shell script with all steps: Create → Read → Update → Delete → Verify
   - Success criteria checklist
   - Copy-paste ready test script

5. Filter Validation - Edge Cases.yml
   - 12 different validation test cases
   - Empty names, missing fields, invalid UUIDs
   - Unicode support (emoji, CJK characters)
   - Malformed JSON handling
   - Special characters and XSS attempts

Documentation Features:
- {{base_url}} variable substitution
- auth: inherit for authentication
- Comprehensive docs: sections with examples
- Shell commands ready to copy-paste
- Expected status codes and responses
- Error handling examples
- Security best practices

Total: 9 YAML files covering all CRUD operations and edge cases

Usage:
- Import into Bruno/Postman for API testing
- Use for manual testing during development
- Reference for API contract validation
- Example curl commands for documentation

Part of: Saved Filters Implementation (Phase 5: Testing & Documentation)
Related: #saved-filters-feature

bruno/saved-filters/Create Saved Filter.yml

@@ -0,0 +1,114 @@
+info:
+  name: Create Saved Filter
+  type: http
+  seq: 2
+http:
+  method: POST
+  url: '{{base_url}}/api/saved-filters'
+  auth: inherit
+  body:
+    type: json
+    jsonBody: "{\n    \"name\": \"My Sci-Fi Books\",\n    \"resource_type\":\
+      \ \"media-items\",\n    \"filters\": {\n      \"genre_filter\": \"Science Fiction\"\
+      ,\n      \"sort\": \"title ASC\",\n      \"author_filter\": \"\"\n    }\n\
+      }"
+
+docs: |-
+  ## Create Saved Filter
+
+  Creates a new saved filter for the authenticated user.
+
+  **Method:** POST
+
+  **Endpoint:** /api/saved-filters
+
+  **Authentication:** Required (Bearer token)
+
+  **Request Body:**
+  ```json
+  {
+    "name": "My Sci-Fi Books",
+    "resource_type": "media-items",
+    "filters": {
+      "genre_filter": "Science Fiction",
+      "sort": "title ASC",
+      "author_filter": "",
+      "series_filter": ""
+    }
+  }
+  ```
+
+  **Required Fields:**
+  - `name` (string, required): Filter name
+    - Must be unique per user + resource type combination
+    - Maximum 100 characters
+    - Cannot be empty
+  - `resource_type` (string, required): Type of resource to filter
+    - Examples: "media-items", "collections", "devices"
+    - Must match valid resource types
+  - `filters` (object, required): Key-value pairs of filter criteria
+    - Flexible structure - any valid filter fields
+    - Serialized as JSONB in database
+
+  **Common Filter Fields for media-items:**
+  - `search`: General search term
+  - `author_filter`: Filter by author name
+  - `genre_filter`: Filter by genre
+  - `series_filter`: Filter by series
+  - `language_filter`: Filter by language
+  - `year_min`: Minimum copyright year
+  - `year_max`: Maximum copyright year
+  - `has_cover`: Boolean for cover image
+  - `sort`: Sort order (e.g., "title ASC", "created_at DESC")
+
+  **Response:**
+  ```json
+  {
+    "id": "550e8400-e29b-41d4-a716-446655440000",
+    "name": "My Sci-Fi Books",
+    "resource_type": "media-items",
+    "filters": {
+      "genre_filter": "Science Fiction",
+      "sort": "title ASC"
+    },
+    "created_at": "2024-03-20T12:00:00Z",
+    "updated_at": "2024-03-20T12:00:00Z"
+  }
+  ```
+
+  **Status Codes:**
+  - 201: Created - Filter successfully created
+  - 400: Bad Request - Invalid request body or missing required fields
+  - 401: Unauthorized - Invalid or missing authentication token
+  - 409: Conflict - Filter with this name already exists for this resource type
+
+  **Error Response Examples:**
+
+  Duplicate name error:
+  ```json
+  {
+    "error": "filter with name 'My Sci-Fi Books' already exists for this resource type"
+  }
+  ```
+
+  **Example Usage:**
+  ```bash
+  curl -X POST \
+    -H "Authorization: Bearer YOUR_TOKEN" \
+    -H "Content-Type: application/json" \
+    -d '{
+      "name": "My Sci-Fi Books",
+      "resource_type": "media-items",
+      "filters": {
+        "genre_filter": "Science Fiction",
+        "sort": "title ASC"
+      }
+    }' \
+    "{{base_url}}/api/saved-filters"
+  ```
+
+  **Validation Rules:**
+  - Name must be unique per user + resource type
+  - Name cannot be empty or whitespace only
+  - Resource type must be valid
+  - Filters object must be provided (can be empty object {})