feat(mc): add midnight commander with declarative config

Public baseline module: installs `mc` plus `ouch` (backs the F2 pack/unpack
entries, archive format inferred from the extension), and ships `ini`, `menu`,
and a generated `panels.ini` into `$XDG_CONFIG_HOME/mc`.

`local.mc.otherDir` exposes the other-panel start dir as an option defaulting
to `config.home.homeDirectory`, so the one personal value isn't baked in. The
F2 user menu is trimmed to the entries that match this config (imv/zathura/mpv
openers, ouch pack/unpack, man view); the stock rcp/uudecode/news/latex cruft
is dropped. `auto_save_setup=false` keeps mc from rewriting the read-only store
symlinks on exit.

modules/assets/mc/menu

@@ -0,0 +1,30 @@
+shell_patterns=0
+
+# F2 user menu. Format macros: %f current file · %d current dir · %s tagged
+# files else current · %t tagged files · %D other panel's dir. Full list: mc(1).
+
+c       Pack selected into an archive (ouch — format from the name's extension)
+        NAME=%{Archive name, e.g. stuff.tar.zst}
+        ouch compress %s "$NAME"
+
+x       Unpack archive here (ouch)
+        ouch decompress %f
+
+i       Open file with image viewer (imv)
+        imv %f
+
+I       Open current directory with image viewer (imv)
+        imv %d
+
+p       Open file with document viewer (zathura)
+        zathura %f
+
+v       Play file with mpv
+        mpv %f
+
+V       Play current directory with mpv
+        mpv %d
+
+m       View a man page
+        MAN=%{Enter manual name}
+        %view{ascii,nroff} MANROFFOPT='-c -Tlatin1' MAN_KEEP_FORMATTING=1 man -P cat "$MAN"