feat(mobile): Expo companion app [beta] (#1245)

Co-authored-by: Orca <help@stably.ai>

.github/workflows/mobile-build.yml

@@ -0,0 +1,71 @@
+name: Mobile Release
+
+on:
+  push:
+    tags:
+      - 'mobile-v*'
+  workflow_dispatch:
+
+jobs:
+  android-build:
+    runs-on: ubuntu-latest
+
+    # Why: the "Create GitHub Release" step below uses the default GITHUB_TOKEN
+    # to call `gh release create`, which requires contents:write. Without this,
+    # the job builds the APK fine but fails at release time with
+    # "HTTP 403: Resource not accessible by integration".
+    permissions:
+      contents: write
+
+    defaults:
+      run:
+        working-directory: mobile
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 24
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          run_install: false
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Setup JDK 17
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 17
+
+      - name: Expo prebuild
+        run: npx expo prebuild --platform android --no-install
+
+      - name: Build Android release APK
+        run: cd android && ./gradlew assembleRelease
+
+      - name: Upload APK artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: orca-mobile-apk
+          path: mobile/android/app/build/outputs/apk/release/*.apk
+
+      - name: Create GitHub Release
+        if: startsWith(github.ref, 'refs/tags/mobile-v')
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          tag="${GITHUB_REF#refs/tags/}"
+          gh release create "$tag" \
+            --repo "$GITHUB_REPOSITORY" \
+            --title "Orca Mobile $tag" \
+            --prerelease \
+            --latest=false \
+            --generate-notes \
+            android/app/build/outputs/apk/release/*.apk

.github/workflows/mobile.yml

@@ -0,0 +1,43 @@
+name: Mobile Checks
+
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+      - ready_for_review
+    paths:
+      - 'mobile/**'
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+
+    defaults:
+      run:
+        working-directory: mobile
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version-file: package.json
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          run_install: false
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Typecheck
+        run: npx tsc --noEmit
+
+      - name: Lint
+        run: pnpm lint
+