fix: never leave Steam a file it would reinstall itself over

The patch that keeps the script's length was the good path and appending was
the fallback, with -noverifyfiles on everything that starts Steam to cover for
it. That cover does not exist.

Steam checks its files at the shutdown it runs itself, not only at a start
somebody handed arguments to, and that run carries no -noverifyfiles whatever
the session was started with. One wrong length there costs the whole client
package downloaded, extracted and installed again - and the client quits at the
end of it instead of coming up, which is the "Steam just closed itself" that
this was seen as:

    BVerifyInstalledFiles: steamwebhelper.sh is 130 bytes, expected 84
    Update wird heruntergeladen ... Paket wird extrahiert ...
    Aktualisierung abgeschlossen, Steam wird geladen ... Shutdown

So the flag now either fits in the space the comments give back or it is not
written at all, and the status screen says Steam is not patched. No autoscroll
in the interface is a far smaller thing than a client that reinstalls itself.

With no growing patch left to prop up, -noverifyfiles has nothing to do and is
gone with everything that carried it: Steam's launcher entry, its autostart
entry, the shortcuts on the desktop and the ones it writes for single games.
Steam repairs its own installation again. An installation from an older version
is taken back once through the flag scheme, and a patch that version appended
is rebuilt to fit at the next apply - or taken back, if the comments cannot pay
for it.

src/lib/patch.sh

@@ -410,15 +410,6 @@ mca_desktop_apply() {
 #   The desktop folder, where a shortcut somebody dragged out of the menu -
 #   or asked Steam for - lives and nowhere else.
 #
-# Steam is in both, even though it is not a Chromium process itself: its
-# entries need -noverifyfiles exactly like the menu one. The autostart entry is
-# the one most likely to exist, because Steam writes it as soon as "run at
-# startup" is ticked; without it a Steam started at login restores the patched
-# web helper script and the watcher patches it back, over and over. The desktop
-# ones are the gap behind "autoscroll works, except sometimes": starting a game
-# from the desktop is a Steam start like any other, and a Steam start without
-# the switch costs the interface its autoscroll for the rest of the session.
-#
 # Neither can be shadowed from anywhere, so both are edited where they stand,
 # with the original kept.
 
@@ -426,11 +417,10 @@ mca_desktop_apply() {
 # One desktop entry that lives outside the XDG search path, edited where it is
 # because there is nowhere to shadow it from.
 #
-# Anything that starts Steam gets Steam's own switch; a Chromium application
-# gets the flag. What decides whether a Chromium application here is in scope
-# differs by where the entry came from, which is what the gate says: an
-# autostart entry follows the autostart setting, a shortcut follows the same
-# rules as the application it is a shortcut to.
+# What decides whether an application here is in scope differs by where the
+# entry came from, which is what the gate says: an autostart entry follows the
+# autostart setting, a shortcut follows the same rules as the application it is
+# a shortcut to.
 _mca_entry_patch_inplace() {
 	local file="$1" gate="$2"
 	local id prog packaging=native content backup kind
@@ -456,30 +446,29 @@ _mca_entry_patch_inplace() {
 		packaging=snap
 	fi
 
-	if mca_prog_is_steam "$prog"; then
-		[[ $CFG_STEAM == yes ]] || return 0
-		content="$(_mca_desktop_transform "$file" "$MCA_MARK_INPLACE" \
-			"$MCA_STEAM_LAUNCH_FLAG" "$(mca_steam_flag_position "$packaging")")"
+	# An entry that starts Steam is left where it is. Steam takes nothing
+	# from a command line that would help, and what it does take belongs to
+	# the web helper script in its own installation.
+	mca_prog_is_steam "$prog" && return 0
+
+	case "$packaging" in
+		flatpak) mca_flatpak_is_chromium "${prog#flatpak:}" || return 0 ;;
+		snap)    mca_snap_is_chromium "${prog#snap:}" || return 0 ;;
+		*)       mca_is_chromium "$prog" || return 0 ;;
+	esac
+
+	mca_desktop_is_browser && kind=browser || kind=app
+
+	if [[ $gate == autostart ]]; then
+		[[ $CFG_AUTOSTART == yes ]] || return 0
 	else
-		case "$packaging" in
-			flatpak) mca_flatpak_is_chromium "${prog#flatpak:}" || return 0 ;;
-			snap)    mca_snap_is_chromium "${prog#snap:}" || return 0 ;;
-			*)       mca_is_chromium "$prog" || return 0 ;;
-		esac
-
-		mca_desktop_is_browser && kind=browser || kind=app
-
-		if [[ $gate == autostart ]]; then
-			[[ $CFG_AUTOSTART == yes ]] || return 0
-		else
-			id="${file##*/}"; id="${id%.desktop}"
-			mca_kind_wanted "$kind" "$id" "$packaging" || return 0
-		fi
-
-		content="$(_mca_desktop_transform "$file" "$MCA_MARK_INPLACE" \
-			"$(mca_flags "$kind")")"
+		id="${file##*/}"; id="${id%.desktop}"
+		mca_kind_wanted "$kind" "$id" "$packaging" || return 0
 	fi
 
+	content="$(_mca_desktop_transform "$file" "$MCA_MARK_INPLACE" \
+		"$(mca_flags "$kind")")"
+
 	[[ -n $content ]] || return 0
 	[[ "$content" == "$(< "$file")" ]] && return 0