graphiti_service.py: bridge driver._search_ops to driver.search_interface

graphiti-core 0.29.0 builds FalkorSearchOperations as driver._search_ops in
FalkorDriver.__init__ but never assigns it to driver.search_interface.
search_utils.py dispatches on search_interface; without this one-line bridge
it falls back to interpreted-Cypher cosine math doing full table scans for
every entity dedup similarity check.

Combined with the vendored patches in graphiti_patches/ (restored in the
previous commit d2ec20e), this activates FalkorDB's native vector index for
the dedup similarity path. Empirical impact (per the original f645b74 commit
message): single-episode add_episode against a ~4,277-entity graph went from
indefinite hang to ~8.2 seconds.

Surgical restore: cherry-picks only the bridge code from f645b74 — not the
Pattern 1 async job model, not the v2.4 extraction instructions, neither of
which we want. Default extraction posture (taxonomy-naïve) stays the
operating mode. Rich-extraction story remains a BirdAI concern.

scripts/graphiti_service.py

@@ -75,6 +75,17 @@ async def lifespan(app: FastAPI):
         max_coroutines=2,
     )
     await graphiti_instance.build_indices_and_constraints()
+    # Bridge driver._search_ops to driver.search_interface — graphiti-core 0.29.0
+    # builds FalkorSearchOperations as driver._search_ops in FalkorDriver.__init__
+    # but never assigns it to driver.search_interface. search_utils.py dispatches
+    # on driver.search_interface; without this assignment it falls back to
+    # interpreted-Cypher cosine math (full table scans). Together with the
+    # vendored patches in graphiti_patches/, this activates FalkorDB's native
+    # vector index for entity dedup similarity search.
+    if (hasattr(graphiti_instance.driver, "_search_ops")
+            and graphiti_instance.driver.search_interface is None):
+        graphiti_instance.driver.search_interface = graphiti_instance.driver._search_ops
+        log.info("Wired driver.search_interface = driver._search_ops (vector index path active)")
     log.info(f"Graphiti ready — provider: {LLM_PROVIDER}, group: {GROUP_ID}")
     yield
     await graphiti_instance.close()