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

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

@@ -0,0 +1,47 @@
+{
+  "fixture": "synthetic SQLite metadata and text; no filesystem extraction or semantic inference",
+  "files": 1000000,
+  "documents": 100000,
+  "seed_seconds": 0.0,
+  "migration_seconds": 19.651645,
+  "fixture_reused": true,
+  "database_bytes": 633917440,
+  "database_path": "target/benchmarks/full.db",
+  "architecture": "x86_64",
+  "os": "windows",
+  "cpu_only": true,
+  "queries": [
+    {
+      "query": "invoice_0999999.txt",
+      "samples": 20,
+      "p50_ms": 115.7827,
+      "p95_ms": 127.39,
+      "target_p95_ms": 50.0,
+      "target_met": false
+    },
+    {
+      "query": "invoice_",
+      "samples": 20,
+      "p50_ms": 0.4833,
+      "p95_ms": 1.734,
+      "target_p95_ms": 50.0,
+      "target_met": true
+    },
+    {
+      "query": "marker0099999",
+      "samples": 20,
+      "p50_ms": 0.3963,
+      "p95_ms": 0.5996,
+      "target_p95_ms": 150.0,
+      "target_met": true
+    },
+    {
+      "query": "cancellation",
+      "samples": 20,
+      "p50_ms": 105.1206,
+      "p95_ms": 112.6383,
+      "target_p95_ms": 150.0,
+      "target_met": true
+    }
+  ]
+}