Complete Phase 9: Final validation for identifier standardization

- Fix search API key extraction from link slugs
- All 1006 tests pass
- All 19 performance tests pass
- Manual end-to-end testing verified
- Key lookup performance: O(1) ~0.11μs per lookup

Phase 9 tasks completed:
- Task 9.1: Full test suite validation
- Task 9.2: Manual end-to-end testing
- Task 9.3: Performance testing

All identifier standardization phases (1-9) now complete.

src/server/api/anime.py

@@ -529,8 +529,12 @@ async def _perform_search(
                 )
                 
                 # If key is empty, try to extract from link
-                if not key and link and "/anime/stream/" in link:
-                    key = link.split("/anime/stream/")[-1].split("/")[0]
+                if not key and link:
+                    if "/anime/stream/" in link:
+                        key = link.split("/anime/stream/")[-1].split("/")[0]
+                    elif link and "/" not in link:
+                        # Link is just a slug (e.g., "attack-on-titan")
+                        key = link
             else:
                 # Extract key (primary identifier)
                 key = getattr(match, "key", "") or getattr(match, "id", "")
@@ -545,8 +549,12 @@ async def _perform_search(
                 missing = getattr(match, "missing_episodes", {})
                 
                 # If key is empty, try to extract from link
-                if not key and link and "/anime/stream/" in link:
-                    key = link.split("/anime/stream/")[-1].split("/")[0]
+                if not key and link:
+                    if "/anime/stream/" in link:
+                        key = link.split("/anime/stream/")[-1].split("/")[0]
+                    elif link and "/" not in link:
+                        # Link is just a slug (e.g., "attack-on-titan")
+                        key = link
 
             summaries.append(
                 AnimeSummary(