refactor: overhaul NFO settings UI and backend

- Rework nfo-settings page with improved styling and layout
- Update edit-modal and context-menu with enhanced functionality
- Refactor NFO API endpoints and models
- Remove deprecated test_nfo_diagnostics_repair.py
- Clean up tasks.md documentation

src/server/models/nfo.py

@@ -372,6 +372,20 @@ class NfoDiagnosticsResponse(BaseModel):
     )
 
 
+class NfoSeriesDiagnostics(BaseModel):
+    """Diagnostics for a single series in the needs-repair list."""
+
+    key: str = Field(..., description="Series unique key")
+    name: str = Field(..., description="Series display name")
+    folder: str = Field(..., description="Series folder name")
+    has_nfo: bool = Field(..., description="Whether tvshow.nfo exists")
+    missing_tags: List[str] = Field(
+        default_factory=list,
+        description="List of missing required tag names"
+    )
+    tmdb_id: Optional[int] = Field(None, description="TMDB ID if available")
+
+
 class NfoRepairResponse(BaseModel):
     """Response after NFO repair attempt."""