feat(ai): add my/copy-region-as-path-tag helper and binding

ai.el

@@ -172,11 +172,30 @@
     (gptel-rewrite-region (region-beginning) (region-end)
                           "Fix spelling, grammar, and improve clarity. Keep the same tone and style.")))
 
+(defun my/copy-region-as-path-tag ()
+  "Copy the current region as a path tag: @path/to/file.ext:start-end"
+  (interactive)
+  (if (use-region-p)
+      (let* ((filename (file-relative-name (buffer-file-name) (doom-project-root)))
+             (start-line (line-number-at-pos (region-beginning)))
+             ;; If region ends at beginning of a line, we want the previous line
+             (end-pos (1- (region-end)))
+             (end-line (line-number-at-pos (max (region-beginning) end-pos)))
+             (tag (format "@%s:%d-%d" filename start-line end-line)))
+        (kill-new tag)
+        (message "Copied: %s" tag))
+    (let* ((filename (file-relative-name (buffer-file-name) (doom-project-root)))
+           (line (line-number-at-pos))
+           (tag (format "@%s:%d" filename line)))
+      (kill-new tag)
+      (message "Copied: %s" tag))))
+
 ;; Add keybindings for helper functions
 (map! :leader
       (:prefix "A"
        :desc "Quick explain" "e" #'my/gptel-quick-explain-region
-       :desc "Proofread text" "p" #'my/gptel-proofread-region))
+       :desc "Proofread text" "p" #'my/gptel-proofread-region
+       :desc "Copy path tag" "t" #'my/copy-region-as-path-tag))
 
 ;;; Claude Code Configuration
 
@@ -332,6 +351,4 @@
 ;;     (add-hook 'eat-mode-hook
 ;;               (lambda ()
 ;;                 (setq-local show-trailing-whitespace nil))))
-;;   (map! :leader
-;;         (:prefix ("C" . "claude-code")
 ;;          :desc "Claudemacs menu" "E" #'claudemacs-transient-menu)))