feat: add NFO scan after rescan and year caching

- Add nfo_scan_after_rescan config option (default: true)
- Implement year caching in AniworldLoader and EnhancedAniWorldLoader
- Make get_year abstract method in base provider
- Run NFO validation/creation after scheduled rescan completes
- Add _YearDict cache to avoid re-extracting year from HTML

src/server/models/config.py

@@ -39,6 +39,12 @@ class SchedulerConfig(BaseModel):
         description="Automatically queue and start downloads for all missing "
                     "episodes after a scheduled rescan completes.",
     )
+    nfo_scan_after_rescan: bool = Field(
+        default=True,
+        description="Run NFO validation and creation after a scheduled rescan "
+                    "completes. Checks each series folder for tvshow.nfo and "
+                    "creates or fills missing properties.",
+    )
     # Legacy alias fields — read via Pydantic alias
     auto_download: Optional[bool] = Field(default=None, alias="auto_download")