feat(anime): rename NFO Diagnostics to Anime Settings + add edit endpoints

Replaces the read-only 'NFO Diagnostics' page with a full per-anime
Settings page reached from the right-click context menu on series cards.
Users can now view and edit key, name, folder, tmdb_id, tvdb_id and site
for each anime; changes are persisted to the DB and optionally written
back to the NFO file or used to regenerate it.

Backend
- Rename NfoDiagnosticsResponse -> NfoSettingsResponse,
  NfoSeriesDiagnostics -> NfoSeriesSettings
- Rename get_nfo_diagnostics -> get_nfo_settings,
  repair_nfo -> repair_nfo_settings
- Fix nfo.py bug: repair was calling non-existent
  update_series_nfo_status(); now uses update_nfo_status() and an
  explicit AnimeSeriesService.update(nfo_path=...)
- New endpoints on /api/anime/{key}:
    GET  /settings            -> AnimeSettingsResponse
    PUT  /settings            -> AnimeSettingsResponse
                                 (body: name/folder/tmdb_id/tvdb_id/site,
                                  options: apply_to_nfo, rename_disk)
    POST /regenerate-nfo      -> AnimeSettingsRegenerateNfoResponse
- New Pydantic models: AnimeSettingsResponse,
  AnimeSettingsUpdateRequest, AnimeSettingsRegenerateNfoResponse
- /anime/settings page route; /settings/nfo now 301-redirects to it

Frontend
- New AniWorld.AnimeSettingsManager JS module (single-page form,
  no tabs) with public API init/loadSeries/saveSettings/regenerateNfo/
  validateField/populateForm/showSaveSuccess/showError
- New anime-settings.html template + anime-settings.css
- Right-click menu: data-action 'nfo-diagnostics' replaced by
  'anime-settings' (label 'Anime Settings'), navigates to
  /anime/settings?key=...
- Library 'Open NFO Diagnostics' link renamed to 'Open Anime Settings'

Bug fix
- context-menu click handler was calling hide() BEFORE building the
  navigation URL, which cleared currentSeriesKey to null and produced
  /anime/settings?key=null. Captures the key into a local const first.
  Regression-locked by tests/frontend/unit/context_menu.test.js.

Tests
- 21 new pytest tests in tests/api/test_anime_settings_endpoints.py
  (GET/PUT/regenerate-nfo, auth, validation, nfo-repair bug regression)
- tests/api/test_nfo_endpoints.py trimmed to 6 focused tests
- 31 new Vitest unit tests for AnimeSettingsManager
- 5 new Vitest unit tests for ContextMenu (incl. source-invariant
  regression guard for the hide()-before-key bug)
- 5 new Playwright E2E tests covering right-click, direct nav,
  legacy /settings/nfo redirect, and context-menu labels
- New vitest.config.js (environment: happy-dom)

Docs
- Docs/API.md: new section 'Anime Settings Endpoints'
- Docs/CHANGELOG.md: documents the rename and the context-menu bug fix

Verified
- pytest: 27/27 (21 new + 6 trimmed nfo)
- vitest: 36/36 (31 anime-settings + 5 context-menu)
- playwright e2e: 5/5

src/server/api/nfo.py

@@ -1,6 +1,6 @@
 """NFO Management API endpoints.
 
-Provides endpoints for NFO diagnostics, repair, and validation for anime series.
+Provides endpoints for NFO settings, repair, and validation for anime series.
 """
 import logging
 import os
@@ -11,9 +11,9 @@ from pydantic import BaseModel
 
 from src.config.settings import settings
 from src.server.models.nfo import (
-    NfoDiagnosticsResponse,
     NfoRepairResponse,
-    NfoSeriesDiagnostics,
+    NfoSeriesSettings,
+    NfoSettingsResponse,
 )
 from src.server.services.anime_service import AnimeService
 from src.server.utils.dependencies import get_anime_service, require_auth
@@ -62,7 +62,7 @@ class NfoNeedsRepairListResponse(BaseModel):
     """Response listing series that need NFO repair."""
 
     total: int
-    series: List[NfoSeriesDiagnostics]
+    series: List[NfoSeriesSettings]
 
 
 def _get_nfo_path(folder: str) -> str:
@@ -123,13 +123,13 @@ async def _get_series_data(
     return None
 
 
-@router.get("/{key}/diagnostics", response_model=NfoDiagnosticsResponse)
-async def get_nfo_diagnostics(
+@router.get("/{key}/diagnostics", response_model=NfoSettingsResponse)
+async def get_nfo_settings(
     key: str,
     _auth: dict = Depends(require_auth),
     anime_service: AnimeService = Depends(get_anime_service),
-) -> NfoDiagnosticsResponse:
-    """Get NFO diagnostics for a specific series.
+) -> NfoSettingsResponse:
+    """Get NFO settings inspection for a specific series.
 
     Checks if tvshow.nfo exists in the series folder and validates
     that required tags are present.
@@ -140,7 +140,7 @@ async def get_nfo_diagnostics(
         anime_service: AnimeService dependency
 
     Returns:
-        NfoDiagnosticsResponse with has_nfo, nfo_path, missing_tags, required_tags
+        NfoSettingsResponse with has_nfo, nfo_path, missing_tags, required_tags
 
     Raises:
         HTTPException 404: If series not found
@@ -165,7 +165,7 @@ async def get_nfo_diagnostics(
     nfo_exists = os.path.isfile(nfo_path)
 
     if not nfo_exists:
-        return NfoDiagnosticsResponse(
+        return NfoSettingsResponse(
             has_nfo=False,
             nfo_path=None,
             missing_tags=REQUIRED_TAGS.copy(),
@@ -175,7 +175,7 @@ async def get_nfo_diagnostics(
     # Parse and check for missing tags
     _, missing = _parse_nfo_file(nfo_path)
 
-    return NfoDiagnosticsResponse(
+    return NfoSettingsResponse(
         has_nfo=True,
         nfo_path=nfo_path,
         missing_tags=missing,
@@ -184,7 +184,7 @@ async def get_nfo_diagnostics(
 
 
 @router.post("/{key}/repair", response_model=NfoRepairResponse)
-async def repair_nfo(
+async def repair_nfo_settings(
     key: str,
     _auth: dict = Depends(require_auth),
     anime_service: AnimeService = Depends(get_anime_service),
@@ -332,12 +332,20 @@ async def _create_or_update_nfo(
     logger.info("Created/updated tvshow.nfo for %s at %s", key, nfo_path)
 
     # Update series NFO status in DB
-    await anime_service.update_series_nfo_status(
+    await anime_service.update_nfo_status(
         key=key,
         has_nfo=True,
-        nfo_path=nfo_path,
     )
 
+    # Also update nfo_path in DB (not part of update_nfo_status signature)
+    from src.server.database.connection import get_db_session
+    from src.server.database.service import AnimeSeriesService
+
+    async with get_db_session() as db:
+        series = await AnimeSeriesService.get_by_key(db, key)
+        if series is not None:
+            await AnimeSeriesService.update(db, series.id, nfo_path=nfo_path)
+
     # Return list of repaired tags (all tags that were missing before)
     return missing_before
 
@@ -411,7 +419,7 @@ async def get_series_needing_repair(
         NfoNeedsRepairListResponse with total count and list of series diagnostics
     """
     all_series = await anime_service.list_series_with_filters()
-    series_needing_repair: List[NfoSeriesDiagnostics] = []
+    series_needing_repair: List[NfoSeriesSettings] = []
 
     anime_dir = getattr(settings, "anime_directory", None)
     if not anime_dir:
@@ -432,7 +440,7 @@ async def get_series_needing_repair(
         nfo_exists = os.path.isfile(nfo_path)
 
         if not nfo_exists:
-            series_needing_repair.append(NfoSeriesDiagnostics(
+            series_needing_repair.append(NfoSeriesSettings(
                 key=key,
                 name=name,
                 folder=folder,
@@ -444,7 +452,7 @@ async def get_series_needing_repair(
         # Parse and check for missing tags
         _, missing = _parse_nfo_file(nfo_path)
         if missing:
-            series_needing_repair.append(NfoSeriesDiagnostics(
+            series_needing_repair.append(NfoSeriesSettings(
                 key=key,
                 name=name,
                 folder=folder,