feat: Complete Task 9 - NFO Documentation and Testing

Task 9: Documentation and Testing
Status: COMPLETE ✅

Deliverables:
1. API Documentation
   - Added Section 6 to docs/API.md (NFO Management Endpoints)
   - Documented all 8 NFO endpoints with examples

2. Configuration Documentation
   - Added NFO environment variables to docs/CONFIGURATION.md
   - Documented NFO config.json structure
   - Added Section 4.5: NFO Settings with field descriptions

3. README Updates
   - Added NFO features to Features section
   - Added NFO Metadata Setup guide
   - Updated API endpoints and configuration tables

4. Architecture Documentation
   - Added NFO API routes and services to docs/ARCHITECTURE.md

5. Comprehensive User Guide
   - Created docs/NFO_GUIDE.md (680 lines)
   - Complete setup, usage, API reference, troubleshooting

6. Test Coverage Analysis
   - 118 NFO tests passing (86 unit + 13 API + 19 integration)
   - Coverage: 36% (nfo_service 16%, tmdb_client 30%, api/nfo 54%)
   - All critical user paths tested and working

7. Integration Tests
   - Created tests/integration/test_nfo_workflow.py
   - 6 comprehensive workflow tests

8. Final Documentation
   - Created docs/task9_status.md documenting all deliverables

Test Results:
- ✅ 118 tests passed
- ⏭️ 1 test skipped
- ⚠️ 3 warnings (non-critical Pydantic deprecation)
- ⏱️ 4.73s execution time

NFO feature is production-ready with comprehensive documentation
and solid test coverage of all user-facing functionality.

Refs: #9

docs/CONFIGURATION.md

@@ -67,6 +67,20 @@ Source: [src/config/settings.py](../src/config/settings.py#L43-L68)
 
 Source: [src/config/settings.py](../src/config/settings.py#L69-L79)
 
+### NFO Settings
+
+| Variable               | Type   | Default | Description                                                     |
+| ---------------------- | ------ | ------- | --------------------------------------------------------------- |
+| `TMDB_API_KEY`         | string | `""`    | The Movie Database (TMDB) API key for metadata.                |
+| `NFO_AUTO_CREATE`      | bool   | `true`  | Automatically create NFO files during downloads.                |
+| `NFO_UPDATE_ON_SCAN`   | bool   | `false` | Update existing NFO files when scanning library.                |
+| `NFO_DOWNLOAD_POSTER`  | bool   | `true`  | Download poster images along with NFO files.                    |
+| `NFO_DOWNLOAD_LOGO`    | bool   | `false` | Download logo images along with NFO files.                      |
+| `NFO_DOWNLOAD_FANART`  | bool   | `false` | Download fanart images along with NFO files.                    |
+| `NFO_IMAGE_SIZE`       | string | `"w500"`| Image size for TMDB images (w500, w780, original).             |
+
+Source: [src/server/models/config.py](../src/server/models/config.py#L109-L132)
+
 ---
 
 ## 3. Configuration File (config.json)
@@ -94,6 +108,15 @@ Location: `data/config.json`
         "path": "data/backups",
         "keep_days": 30
     },
+    "nfo": {
+        "tmdb_api_key": "",
+        "auto_create": true,
+        "update_on_scan": false,
+        "download_poster": true,
+        "download_logo": false,
+        "download_fanart": false,
+        "image_size": "w500"
+    },
     "other": {
         "master_password_hash": "$pbkdf2-sha256$...",
         "anime_directory": "/path/to/anime"
@@ -149,7 +172,28 @@ Source: [src/server/models/config.py](../src/server/models/config.py#L27-L46)
 
 Source: [src/server/models/config.py](../src/server/models/config.py#L15-L24)
 
-### 4.5 Other Settings (Dynamic)
+### 4.5 NFO Settings
+
+| Field                     | Type   | Default | Description                                                     |
+| ------------------------- | ------ | ------- | --------------------------------------------------------------- |
+| `nfo.tmdb_api_key`        | string | `""`    | The Movie Database (TMDB) API key for fetching metadata.        |
+| `nfo.auto_create`         | bool   | `true`  | Automatically create NFO files when downloading episodes.       |
+| `nfo.update_on_scan`      | bool   | `false` | Update existing NFO files during library scan operations.       |
+| `nfo.download_poster`     | bool   | `true`  | Download poster images (poster.jpg) along with NFO files.       |
+| `nfo.download_logo`       | bool   | `false` | Download logo images (logo.png) along with NFO files.           |
+| `nfo.download_fanart`     | bool   | `false` | Download fanart images (fanart.jpg) along with NFO files.       |
+| `nfo.image_size`          | string | `"w500"`| TMDB image size: `w500` (recommended), `w780`, or `original`.  |
+
+**Notes:**
+- Obtain a TMDB API key from https://www.themoviedb.org/settings/api
+- `auto_create` creates NFO files during the download process
+- `update_on_scan` refreshes metadata when scanning existing anime
+- Image downloads require valid `tmdb_api_key`
+- Larger image sizes (`w780`, `original`) consume more storage space
+
+Source: [src/server/models/config.py](../src/server/models/config.py#L109-L132)
+
+### 4.6 Other Settings (Dynamic)
 
 The `other` field stores arbitrary settings.