feat: Add three-tier optimization for maximum performance

Implemented smart caching system that dramatically reduces processing time:

TIER 1 (Fastest): NFO File Check
- If NFO already has NFOGuard dateadded + lockdata, use it directly
- Skips both database queries AND API calls
- Perfect for movies already processed by NFOGuard

TIER 2 (Fast): Database Check
- If database has complete dateadded data, use it
- Skips expensive API calls to TMDB/OMDB/Radarr
- Creates NFO from cached data

TIER 3 (Slowest): Full Processing
- Only when neither NFO nor database have data
- Queries all APIs, processes dates, saves to database

This should dramatically improve full scan performance, especially
on subsequent runs where most movies already have NFOGuard data.

Expected speedup: 90%+ reduction in processing time for warm scans.

nfoguard.py

@@ -970,7 +970,23 @@ class MovieProcessor:
             self.db.upsert_movie_dates(imdb_id, None, None, None, False)
             return
         
-        # Get existing dates
+        # TIER 1: Check if NFO file already has NFOGuard data (fastest - no DB or API calls)
+        nfo_path = movie_path / "movie.nfo"
+        nfo_data = self.nfo_manager.extract_nfoguard_dates_from_nfo(nfo_path)
+        if nfo_data:
+            _log("INFO", f"🚀 Using existing NFOGuard data from NFO file: {nfo_data['dateadded']} (source: {nfo_data['source']})")
+            dateadded = nfo_data["dateadded"]
+            source = nfo_data["source"] 
+            released = nfo_data.get("released")
+            
+            # Update file mtimes if enabled (NFO is already correct)
+            if config.fix_dir_mtimes and dateadded:
+                self.nfo_manager.update_movie_files_mtime(movie_path, dateadded)
+            
+            _log("INFO", f"Completed processing movie: {movie_path.name} (source: {source}) [nfo-only]")
+            return
+            
+        # TIER 2: Check database for existing data
         existing = self.db.get_movie_dates(imdb_id)
         _log("DEBUG", f"Database lookup for {imdb_id}: {existing}")