chore: release v0.4.2 — first post-rename build (cc.agentlabs.opencode)

First tagged release after the ai.opencode.mobile -> cc.agentlabs.opencode
rename. Produces a signed cc.agentlabs.opencode APK on the GitHub release and
refreshes the self-hosted F-Droid repo to the current package — prerequisite
for the F-Droid mainline / IzzyOnDroid submissions.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app.json

@@ -2,7 +2,7 @@
   "expo": {
     "name": "OpenCode",
     "slug": "opencode-mobile",
-    "version": "0.4.1",
+    "version": "0.4.2",
     "orientation": "portrait",
     "scheme": "opencode",
     "userInterfaceStyle": "automatic",