fix(mail): repair account nav, send fallback, and reply handling

Seven config-audit findings in mail-config, each verified against the installed mu4e 1.14 source before changing anything:

- The C-; e account nav commands now require mu4e before searching. The maps register eagerly at startup, but mu4e-search has no autoload cookie, so a nav key pressed before mu4e's first launch signaled void-function.
- With msmtp absent, both send variables now get cj/mail--send-mail-unavailable, which signals a user-error naming msmtp. The old fallback left message-send-mail-function nil (the top-level defvar pre-empts message.el's default), so the first send died with "invalid function: nil".
- I removed the unconditional org-msg-edit-mode advice on the two reply commands. org-msg-post-setup already runs on mu4e-compose-mode-hook and applies org-msg-default-alternatives itself, so the advice forced org-msg onto text-only replies and re-ran a major mode org-msg had already set up.
- I dropped the save-attachment headers action: mu4e-view-save-attachments takes no message argument and reads MIME parts from the view buffer, so it never worked from headers.
- I deleted the obsolete HTML view knobs (mu4e-view-prefer-html and both mu4e-html2text-command sets): the shr-based view has ignored them since mu4e 1.7.
- I reordered the contexts so cjennings.net comes first: with pick-first, gmail-first made gmail the silent default account for the first compose.
- I dropped mu4e-starred-folder (not a mu4e variable, never had an effect) and the obsolete mu4e-maildir alias.

New tests cover the nav-command mu4e load and the msmtp-absent fallback.

1 files changed, 17 insertions, 0 deletions

diff --git a/tests/test-mail-config-transport.el b/tests/test-mail-config-transport.el
index 0240102a..9329ac70 100644
--- a/tests/test-mail-config-transport.el
+++ b/tests/test-mail-config-transport.el
@@ -66,6 +66,23 @@ EXECUTABLES is an alist of program name strings to executable paths."
       (should (equal test-mail-config--warnings
                      '((mail-config . "msmtp not found; SMTP mail sending unavailable")))))))
 
+(ert-deftest test-mail-config-transport-msmtp-missing-sets-descriptive-fallback ()
+  "Error: with msmtp absent, the send functions get a descriptive fallback.
+The old behavior left `message-send-mail-function' nil (the top-level defvar
+pre-empts message.el's default), so the first send died with \"invalid
+function: nil\".  The fallback must be installed on both send variables and
+must signal a `user-error' that names msmtp."
+  (test-mail-config--with-executables nil
+    (let (send-mail-function message-send-mail-function)
+      (cj/mail-configure-smtpmail)
+      (should (eq send-mail-function #'cj/mail--send-mail-unavailable))
+      (should (eq message-send-mail-function #'cj/mail--send-mail-unavailable))
+      (should-error (cj/mail--send-mail-unavailable) :type 'user-error)
+      (condition-case err
+          (cj/mail--send-mail-unavailable)
+        (user-error
+         (should (string-match-p "msmtp" (cadr err))))))))
+
 (ert-deftest test-mail-config-transport-mbsync-present-builds-command ()
   "When mbsync exists, build the mu4e sync command."
   (test-mail-config--with-executables '(("mbsync" . "/usr/bin/mbsync"))