fix(kbsearch): rank FTS correctly, filter before -n, start the daemon. (#5)

Go search took worst BM25 hits (ORDER BY score), cut to -n before --root,
and never called ensureDaemon. Ranking and flag parsing move to a cgo-free
package so CI can fail those regressions without ladybug. --hop errors
instead of being swallowed into the query.

bin/kbsearch/main.go

@@ -8,7 +8,9 @@
 //	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).
+// daemon over localhost HTTP (KBSEARCH_PORT, default 17830) and starts one in
+// the background when none answers. KBSEARCH_NO_DAEMON=1 skips that and embeds
+// in-process instead.
 package main
 
 import (
@@ -41,4 +43,4 @@ func main() {
 		return
 	}
 	os.Exit(runSearch(os.Args[1:]))
-}
+}