fix: package autoload order

This is an old issue that's haunted Doom for a while. I had initially
planned to wait until the switch to Elpaca, but I decided to just sit
down and solve this.

This ensures package autoloads are always written in depth-first
dependency order to Doom's profile init file, preventing load-order
issues like the notorious void-function geiser-activate-implementation
error. `geiser` needs to be built before any `geiser-*` plugins, since
its plugins reference variables/functions in geiser's own autoloads, but
there's no way to enforce package order in `straight--build-cache`
currently, and subsequent package updates (or just deleting package
directories by hand) can change the order of straight's build-cache in
subtle ways.

Fix: #7693
Fix: #7472

lisp/lib/profiles.el

@@ -410,9 +410,19 @@ caches them in `doom--profiles'. If RELOAD? is non-nil, refresh the cache."
   `((defun doom--startup-loaddefs-packages ()
       (let ((load-in-progress t))
         ,@(doom-autoloads--scan
-           (mapcar #'straight--autoloads-file
-                   (nreverse (seq-difference (hash-table-keys straight--build-cache)
-                                             doom-autoloads-excluded-packages)))
+           ;; Create a list of packages starting with the Nth-most dependencies
+           ;; by walking the package dependency tree depth-first. This ensures
+           ;; any load-order constraints in package autoloads are always met.
+           (let (packages)
+             (letf! (defun* walk-packages (pkglist)
+                      (cond ((null pkglist) nil)
+                            ((stringp pkglist)
+                             (walk-packages (nth 1 (gethash pkglist straight--build-cache)))
+                             (cl-pushnew pkglist packages :test #'equal))
+                            ((listp pkglist)
+                             (mapc #'walk-packages (reverse pkglist)))))
+               (walk-packages (mapcar #'symbol-name (mapcar #'car doom-packages))))
+             (mapcar #'straight--autoloads-file (nreverse packages)))
            doom-autoloads-excluded-files
            'literal))
       ,@(when-let* ((info-dirs