feat: add legacy key/data file migration to database

- Add migration_legacy_files_completed flag to SystemSettings model
- Create legacy_file_migration service to migrate series from key/data files
- Integrate legacy migration into initialization_service startup flow
- Add integration tests for legacy file migration
- Update DATABASE.md documentation with migration details
- Fix various test and service issues (nfo_repair, tmdb_client, download_service)
- Add test_database_schema unit tests

src/core/services/tmdb_client.py

@@ -128,7 +128,7 @@ class TMDBClient:
                 # Expired negative cache entry
                 del self._negative_cache[negative_cache_key]
         
-        delay = 2
+        delay = 1
         last_error = None
         
         # Rate limiting: ensure we don't exceed ~35 requests/second
@@ -162,7 +162,7 @@ class TMDBClient:
                             raise TMDBAPIError(f"Resource not found: {endpoint}")
                         elif resp.status == 429:
                             # Rate limit - wait longer with exponential backoff
-                            retry_after = int(resp.headers.get('Retry-After', max(delay * 2, 10)))
+                            retry_after = int(resp.headers.get('Retry-After', max(delay * 2, 2)))
                             logger.warning("Rate limited, waiting %ss", retry_after)
                             await asyncio.sleep(retry_after)
                             continue
@@ -181,7 +181,7 @@ class TMDBClient:
                     if attempt < max_retries - 1:
                         logger.warning("Request timeout (attempt %s), retrying in %ss", attempt + 1, delay)
                         await asyncio.sleep(delay)
-                        delay = min(delay * 2, 30)
+                        delay *= 2
                     else:
                         logger.error("Request timed out after %s attempts", max_retries)
                         
@@ -209,7 +209,7 @@ class TMDBClient:
                     if attempt < max_retries - 1:
                         logger.warning("Request failed (attempt %s): %s, retrying in %ss", attempt + 1, e, delay)
                         await asyncio.sleep(delay)
-                        delay = min(delay * 2, 30)
+                        delay *= 2
                     else:
                         logger.error("Request failed after %s attempts: %s", max_retries, e)