Rename the Fixer to Tune-up

Tab, URL (#/pair/<id>/tune-up; old fixer links still work), job names,
History trigger and docs now say Tune-up.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/api/fixer.go

@@ -6,7 +6,7 @@ import (
 	"github.com/cdnutter/playlink/internal/engine"
 )
 
-// ---- step-by-step fixer ----
+// ---- tune-up (step-by-step library fixing) ----
 
 func (s *Server) handleFixer(w http.ResponseWriter, r *http.Request) {
 	id, _ := idParam(r)
@@ -43,7 +43,7 @@ func (s *Server) handleFixApply(w http.ResponseWriter, r *http.Request) {
 	if !readJSON(w, r, &body) {
 		return
 	}
-	if !s.preAction(w, r, id, "fixer") {
+	if !s.preAction(w, r, id, "tune-up") {
 		return
 	}
 	j, err := s.eng.StartFixApply(id, body)
@@ -51,7 +51,7 @@ func (s *Server) handleFixApply(w http.ResponseWriter, r *http.Request) {
 		opErr(w, err)
 		return
 	}
-	s.log.Info("fixer apply started", "pair", id, "selected", len(body.IDs))
+	s.log.Info("tune-up apply started", "pair", id, "selected", len(body.IDs))
 	writeJSON(w, 202, j)
 }