fix(agents-mobile): set Android/iOS app icon to the Electric mark (#4593)

## Why

The Android app was **rejected from the Google Play Store** under the
Misleading Claims policy: *"App store listing mismatch — your app's
installed icon or name differs from its store listing."*

Root cause: `packages/agents-mobile/app.config.ts` declared **no `icon`
and no `android.adaptiveIcon`**, and the project shipped **no icon
assets**. Since `android/`/`ios/` are gitignored and regenerated by
`expo prebuild` on every EAS build, Expo fell back to its **default
placeholder icon** — the green Android robot — baked into
`mipmap-*/ic_launcher`. The installed launcher icon therefore didn't
match the Electric logo on the Play Store listing.

| | Icon |
|---|---|
| Store listing (hi-res) | ✅ Electric mark (cyan bolt on dark) |
| Installed launcher (before) | ❌ Default green Android robot |

## What changed

- **`assets/icon.png`** — the canonical Electric store-icon artwork
(1024×1024, same mark as `agents-desktop/assets/icon.png`).
- **`assets/adaptive-icon.png`** — Android adaptive foreground: cyan
bolt (`#75FBFD`) centered within the safe zone, transparent background.
- **`app.config.ts`** — set `icon` and `android.adaptiveIcon`
(foreground + `backgroundColor: #101217`).

## Verification

Ran `expo prebuild --platform android` against the new config:
- `mipmap-anydpi-v26/ic_launcher.xml` → adaptive icon with
`background=#101217`, `foreground=ic_launcher_foreground` ✅
- Generated `ic_launcher.webp` renders the **dark square + cyan bolt**,
matching the store listing (green robot gone) ✅
- Confirmed the foreground isn't clipped under a worst-case circular
launcher mask ✅

## Follow-up to clear the rejection

After merge, cut a new EAS build (versionCode auto-increments via the CI
`.build-info.json` flow), upload the AAB, and resubmit for review.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: kevin-dp

.changeset/agents-mobile-app-icon.md

@@ -0,0 +1,5 @@
+---
+"@electric-ax/agents-mobile": patch
+---
+
+Set the Electric app icon (master + Android adaptive icon) so the installed launcher icon matches the Play Store listing instead of Expo's default placeholder.

packages/agents-mobile/app.config.ts

@@ -23,6 +23,7 @@ export default ({ config }: ConfigContext): ExpoConfig =>
       version: packageJson.version,
       runtimeVersion: packageJson.version,
       orientation: `portrait`,
+      icon: `./assets/icon.png`,
       userInterfaceStyle: `automatic`,
       newArchEnabled: true,
       plugins: [
@@ -64,6 +65,10 @@ export default ({ config }: ConfigContext): ExpoConfig =>
         package: applicationId,
         versionCode,
         edgeToEdgeEnabled: true,
+        adaptiveIcon: {
+          foregroundImage: `./assets/adaptive-icon.png`,
+          backgroundColor: `#101217`,
+        },
       },
       extra: {
         ...config.extra,