perf: index filename candidates and avoid full-corpus retrieval scans

crates/searchi-core/benchmarks/results/windows-cpu-full.json

@@ -0,0 +1,45 @@
+{
+  "fixture": "synthetic SQLite metadata and text; no filesystem extraction or semantic inference",
+  "files": 1000000,
+  "documents": 100000,
+  "seed_seconds": 277.2314138,
+  "database_bytes": 309338112,
+  "database_path": "target/benchmarks/full.db",
+  "architecture": "x86_64",
+  "os": "windows",
+  "cpu_only": true,
+  "queries": [
+    {
+      "query": "invoice_0999999.txt",
+      "samples": 20,
+      "p50_ms": 404.75899999999996,
+      "p95_ms": 633.8166,
+      "target_p95_ms": 50.0,
+      "target_met": false
+    },
+    {
+      "query": "invoice_",
+      "samples": 20,
+      "p50_ms": 3385.7561,
+      "p95_ms": 4131.4819,
+      "target_p95_ms": 50.0,
+      "target_met": false
+    },
+    {
+      "query": "marker0099999",
+      "samples": 20,
+      "p50_ms": 311.6295,
+      "p95_ms": 355.7767,
+      "target_p95_ms": 150.0,
+      "target_met": false
+    },
+    {
+      "query": "cancellation",
+      "samples": 20,
+      "p50_ms": 2186.2423,
+      "p95_ms": 2746.9136,
+      "target_p95_ms": 150.0,
+      "target_met": false
+    }
+  ]
+}