release(fdroid): v0.4.3 — fix self-hosted F-Droid publish (v2-only signing)

The self-hosted F-Droid repo (https://dzianisv.github.io/opencode-mobile/fdroid/repo)
has been stuck at v0.4.1 because publish-fdroid crashed in androguard parsing the
CI APK's v2+v3 signature block pair ('NoOverwriteDict' object has no attribute
'append'). Force v1+v2-only signing: gradle flags for local builds, plus a
deterministic apksigner re-sign step in the workflow (expo prebuild regenerates
build.gradle, so the workflow step is the real guarantee). Bump to v0.4.3 /
versionCode 5 so a fresh tag re-runs the publish with the verified bug fixes
(#10 scope fixes, send-error fix) included.

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

app.json

@@ -2,7 +2,7 @@
   "expo": {
     "name": "OpenCode",
     "slug": "opencode-mobile",
-    "version": "0.4.2",
+    "version": "0.4.3",
     "orientation": "portrait",
     "scheme": "opencode",
     "userInterfaceStyle": "automatic",
@@ -34,7 +34,7 @@
     },
     "android": {
       "package": "cc.agentlabs.opencode",
-      "versionCode": 4,
+      "versionCode": 5,
       "usesCleartextTraffic": true,
       "adaptiveIcon": {
         "foregroundImage": "./assets/adaptive-icon.png",