feat: add multimodal search and granular performance diagnostics

docs/evidence/windows-cpu-google-query-diagnostics.json

@@ -0,0 +1,22 @@
+{
+  "date": "2026-10-12",
+  "model": "google/embeddinggemma-2",
+  "runtime": "llama.cpp b11461 with pinned no-logits patch",
+  "device": "cpu",
+  "threads": 1,
+  "test": "google_cpu_debug_query_reports_actual_worker_stages_without_changing_vectors",
+  "test_elapsed_seconds_including_initialization_and_two_queries": 18.09,
+  "debug_normal_cosine": 0.99999999,
+  "diagnostics": {
+    "request_encode_us": 24,
+    "request_write_us": 52,
+    "response_validate_us": 92,
+    "worker_batch_prepare_us": 22,
+    "worker_inference_us": 112914,
+    "worker_pool_normalize_us": 17,
+    "worker_token_count": 13,
+    "worker_tokenization_us": 149,
+    "worker_wait_and_response_decode_us": 113960
+  },
+  "scope": "One actual query diagnostic; native worker clocks are not aligned to Rust. VM had concurrent media inference. No production latency or broad overhead claim."
+}