Fix clear-data to actually delete run_cache entries

- discard_run now deletes from run_cache and pending_runs tables
- Add delete_run_cache() and delete_pending_run() database functions
- Previously clear-data only cleared Redis, leaving DB cache intact

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

database.py

@@ -1207,6 +1207,26 @@ async def list_runs_by_actor(actor_id: str, offset: int = 0, limit: int = 20) ->
         ]
 
 
+async def delete_run_cache(run_id: str) -> bool:
+    """Delete a run from the cache."""
+    async with pool.acquire() as conn:
+        result = await conn.execute(
+            "DELETE FROM run_cache WHERE run_id = $1",
+            run_id
+        )
+        return result == "DELETE 1"
+
+
+async def delete_pending_run(run_id: str) -> bool:
+    """Delete a pending run."""
+    async with pool.acquire() as conn:
+        result = await conn.execute(
+            "DELETE FROM pending_runs WHERE run_id = $1",
+            run_id
+        )
+        return result == "DELETE 1"
+
+
 # ============ Storage Backends ============
 
 async def get_user_storage(actor_id: str) -> List[dict]: