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/types.go

@@ -1,16 +1,14 @@
 // Common types and helpers for kbsearch.
 package main
 
-import "os"
+import (
+	"os"
+
+	"github.com/eSlider/2dph/bin/kbsearch/rank"
+)
 
 func eps() string { return os.Getenv("KBTEST_EPS") }
 
-// Hit is one search result, mirroring the python script's dict shape.
-type Hit struct {
-	ID      string  `json:"id"`
-	Text    string  `json:"text"`
-	Root    string  `json:"root"`
-	Source  string  `json:"-"` // for repo filtering, not in output
-	Score   float64 `json:"score"`
-	Snippet string  `json:"snippet,omitempty"`
-}
+// Hit is the search hit type; ranking lives in package rank so CI can test
+// it without the native ladybug library.
+type Hit = rank.Hit