feat(schema): bulk_search capability flag (fb-42)

- Capabilities.bulk_search: true (snapshot)
- schema.v1 wire required list updated

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/wire-schema/v1/schema.schema.json

@@ -24,7 +24,7 @@
       "required": [
         "json_mode", "ingest_progress", "ingest_cancellation",
         "rag_multi_turn", "search_cache", "incremental_ingest",
-        "streaming_ask", "http_daemon", "mcp_server", "single_file_ingest"
+        "streaming_ask", "http_daemon", "mcp_server", "single_file_ingest", "bulk_search"
       ]
     },
     "models": {