Update mu4e config for mu 1.12.15

- Use symlinked path instead of versioned Cellar path for mu4e
- Add explicit mu4e-mu-binary path for Homebrew on Apple Silicon
- Add transient menu keybinding (C-c m) for mu4e 1.12.9+
- Use message-signature instead of deprecated mu4e-compose-signature
- Remove unused IONOS maildir shortcuts and LKML bookmark

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

lisp/mu4e-config.el

@@ -2,10 +2,15 @@
 
 ;; mu4e should already be loaded from .emacs before this file is loaded
 ;; If not loaded, try to load it
-(add-to-list 'load-path "/opt/homebrew/Cellar/mu/1.12.12/share/emacs/site-lisp/mu/mu4e")
+;; Note: mu4e path is symlinked from Homebrew Cellar
+(add-to-list 'load-path "/opt/homebrew/share/emacs/site-lisp/mu4e")
+
+;; Ensure Emacs can find the mu binary (Homebrew on Apple Silicon)
+(setq mu4e-mu-binary "/opt/homebrew/bin/mu")
+
 (require 'mu4e)
 
-;; HTML rendering configuration for mu4e 1.12
+;; HTML rendering configuration for mu4e 1.12+
 
 ;; Use shr as the default renderer
 (setq mm-text-html-renderer 'shr)
@@ -184,11 +189,7 @@
 
         (:name  "📋 GCC"
          :query "list:gcc.gcc.gnu.org AND NOT flag:trashed"
-         :key ?G)
-
-        (:name "📋 LKML"
-         :query "list:linux-kernel.vger.kernel.org AND NOT flag:trashed"
-         :key ?K)))
+         :key ?G)))
 
 (setq mu4e-maildir-shortcuts
       '(("/Personal/INBOX"    . ?i)
@@ -197,12 +198,7 @@
         ("/Personal/Drafts"   . ?d)
         ("/Personal/Spam   "  . ?S)
         ("/Personal/Archive"  . ?a)
-        ("/Personal/Lists"    . ?l)
-        ("/IONOS/INBOX"       . ?I)
-        ("/IONOS/Sent"        . ?S)
-        ("/IONOS/Trash"       . ?T)
-        ("/IONOS/Drafts"      . ?D)
-        ("/IONOS/Archive"     . ?A)))
+        ("/Personal/Lists"    . ?l)))
 
 ;; Custom function for fuzzy relative timestamps
 (defun my-mu4e-format-date (date)
@@ -319,6 +315,12 @@
 (global-set-key (kbd "C-x m") 'mu4e)
 (global-set-key (kbd "C-x M") 'mu4e-compose-new)
 
+;; Transient menu (mu4e 1.12.9+)
+(with-eval-after-load 'mu4e
+  (require 'mu4e-transient nil t)
+  (when (featurep 'mu4e-transient)
+    (global-set-key (kbd "C-c m") #'mu4e-transient-menu)))
+
 ;; Double-check pandoc is available and being used
 (if (executable-find "pandoc")
     (message "Pandoc found at: %s" (executable-find "pandoc"))
@@ -378,9 +380,8 @@
         (:list-id "boost-announce.lists.boost.org" :name "Boost-Announce")
         (:list-id "boost-interest.lists.boost.org" :name "Boost-Interest")))
 
-;; Signature
-(setq mu4e-compose-signature
-      "Jens")
+;; Signature (mu4e 1.12+ uses message-signature)
+(setq message-signature "Jens")
 
 ;; SMTP Configuration for sending mail
 (require 'smtpmail)