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

bin/kbsearch/main.go

@@ -0,0 +1,44 @@
+// bin/kbsearch - the Go implementation of bin/kb/search (nested module so the
+// root `go test ./...` and CI never compile it against native ladyships).
+//
+// Usage (built/run by ./bin/kb/search):
+//
+//	kbsearch "query" [--root facts|info] [--repo P] [-n N] [--json]
+//	kbsearch serve [port]           start the embedding daemon
+//	kbsearch --list-model           print the resolved model dir
+//
+// The potion-multilingual model is loaded only in `serve`; a CLI reuses the
+// daemon over localhost HTTP (falling back to in-process embedding).
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+)
+
+func main() {
+	if len(os.Args) > 1 && os.Args[1] == "serve" {
+		port := 17830
+		if len(os.Args) > 2 {
+			if p, err := strconv.Atoi(os.Args[2]); err == nil {
+				port = p
+			}
+		}
+		if err := serve(port); err != nil {
+			log.Fatalf("kbsearch serve: %v", err)
+		}
+		return
+	}
+	if len(os.Args) > 1 && os.Args[1] == "--list-model" {
+		dir, err := modelDir()
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+		fmt.Println(dir)
+		return
+	}
+	os.Exit(runSearch(os.Args[1:]))
+}