chore(users/sterni/mblog): rename apple-note to mail-note

The type identifier Apple uses is com.apple.mail-note, so “Mail Note” is
actually the best way to refer to this format. Not only doesn't it
include a trademark, but it's also more accurate. The iOS and macOS
Notes.app(s) allow authoring Notes to be saved in iCloud which seems to
use a different API and/or storage format (at least these notes are no
longer accessible via IMAP). In this sense they are “Apple Notes”, but
not “Mail Notes”.

Change-Id: I2fd3d3bd253ed39adf7965008290f7d1e622831d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12815
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>

users/sterni/mblog/default.nix

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-3.0-only
-# SPDX-FileCopyrightText: Copyright (C) 2022-2023 by sterni
+# SPDX-FileCopyrightText: Copyright (C) 2022-2024 by sterni
 { depot, pkgs, ... }:
 
 (depot.nix.buildLisp.program {
@@ -9,8 +9,8 @@
     ./packages.lisp
     ./config.lisp
     ./maildir.lisp
-    ./transformer.lisp
-    ./note.lisp
+    ./mail-note/html-transformer.lisp
+    ./mail-note/note.lisp
     ./mblog.lisp
     ./cli.lisp
   ];