iso: audit-sweep UID, bakery update, lockfile, welcome, autostart

Resolve MAIN_USER after deleting liveuser so Snapper and skel target the
installed account. Wrap bakery update with sudo -n/pkexec for /usr/local.
Pin bakery and bread-theme 0.7.4; require bread-emit and bread-module-host.
Make Calamares internet check non-blocking against breadway.dev. Autostart
breadlock listen. Smoke avahi-daemon.socket to match post-install.

iso/airootfs/etc/calamares/modules/welcome.conf

@@ -3,9 +3,19 @@ showSupportUrl: false
 showKnownIssuesUrl: false
 showReleaseNotesUrl: false
 
+# 3.4.2 schema: `check` is shown; only `required` blocks Next. Internet is
+# informational so offline installs proceed. Do not probe archlinux.org.
 requirements:
   requiredStorage: 20
   requiredRam: 2.0
-  checkInternet: true
-  checkPower: true
-  internetCheckUrl: "https://archlinux.org"
+  internetCheckUrl: "https://breadway.dev"
+  check:
+    - storage
+    - ram
+    - power
+    - internet
+    - root
+  required:
+    - storage
+    - ram
+    - root