fix(lint): staticcheck S1030, QF1002 and remove unused _ctx stub

internal/tools/tool.go

@@ -1,7 +1,6 @@
 package tools
 
 import (
-	"context"
 	"encoding/json"
 
 	"gitea.d-ma.be/mathias/gitea-mcp/internal/registry"
@@ -21,8 +20,6 @@ func parseArgs(raw json.RawMessage, dst any) error {
 	return json.Unmarshal(raw, dst)
 }
 
-func _ctx(ctx context.Context) context.Context { return ctx } // stub for future hooks
-
 // capLimit returns a sane page size: 0 or negative → def, > 50 → 50.
 func capLimit(in, def int) int {
 	if in <= 0 {