kbsearch: Go implementation with daemon model serving

- New nested module bin/kbsearch with Go implementation of bin/kb/search
- Embedding model (potion-multilingual-128M) served by localhost daemon
  so repeated CLI calls reuse the loaded model
- Bash launcher bin/kb/search builds binary on first run, caches to var/bin/
- Hybrid FTS + vector search (RRF k=60) matching Python kblib behavior
- YAML output via port of yamlout.py (ordered keys, same format)
- JSON output with proper field order
- All flags: --root, --repo, -n, --json, --list-model
- Root go.mod reverted to 1.25.0 (kbsearch is isolated nested module)
- CI passes: go test ./... and go vet ./... unaffected by kbsearch

.gitignore

@@ -8,4 +8,5 @@ __pycache__/
 .DS_Store
 *.env
 .env
-.secrets/
+.secrets/
+lib-ladybug/