feat(files): introduce upload_file tool for staging files and enhance save_file documentation

internal/mcpserver/schema.go

@@ -47,7 +47,7 @@ func logToolCall[In any, Out any](logger *slog.Logger, toolName string, handler
 		result, out, err := handler(ctx, req, in)
 
 		completionAttrs := append([]any{}, attrs...)
-		completionAttrs = append(completionAttrs, slog.Duration("duration", time.Since(start)))
+		completionAttrs = append(completionAttrs, slog.String("duration", formatLogDuration(time.Since(start))))
 		if err != nil {
 			completionAttrs = append(completionAttrs, slog.String("error", err.Error()))
 			logger.Error("mcp tool completed", completionAttrs...)
@@ -70,6 +70,18 @@ func truncateArgs(args any) string {
 	return string(b[:maxLoggedArgBytes]) + fmt.Sprintf("… (%d bytes total)", len(b))
 }
 
+func formatLogDuration(d time.Duration) string {
+	if d < 0 {
+		d = -d
+	}
+
+	totalMilliseconds := d.Milliseconds()
+	minutes := totalMilliseconds / 60000
+	seconds := (totalMilliseconds / 1000) % 60
+	milliseconds := totalMilliseconds % 1000
+	return fmt.Sprintf("%02d:%02d:%03d", minutes, seconds, milliseconds)
+}
+
 func setToolSchemas[In any, Out any](tool *mcp.Tool) error {
 	if tool.InputSchema == nil {
 		inputSchema, err := jsonschema.For[In](toolSchemaOptions)