[feat] support standalone iOS and Android releases

.github/workflows/build-android.yml

@@ -3,6 +3,12 @@ name: Build Android
 on:
   workflow_dispatch:
   workflow_call:
+    inputs:
+      source_tag:
+        description: "Existing source tag for a standalone Android release."
+        required: false
+        type: string
+        default: ""
     outputs:
       version:
         description: "Independent Android version and build date."
@@ -11,6 +17,7 @@ on:
     paths:
       - ".github/workflows/build-android.yml"
       - ".github/workflows/build.yml"
+      - ".github/workflows/release-mobile.yml"
       - ".gitmodules"
       - "LICENSE"
       - "apps/android/**"
@@ -32,11 +39,14 @@ jobs:
       version: ${{ steps.package.outputs.version }}
     env:
       XMAKE_VERSION: "3.1.1"
+      CROSSDESK_SOURCE_TAG: ${{ inputs.source_tag || '' }}
+      CROSSDESK_RELEASE_BUILD: ${{ inputs.source_tag && 'YES' || 'NO' }}
     steps:
       - name: Checkout code
         uses: actions/checkout@v5
         with:
           fetch-depth: 0
+          ref: ${{ inputs.source_tag || github.ref }}
           submodules: recursive
           persist-credentials: false
 
@@ -120,13 +130,19 @@ jobs:
               raise ValueError(f"Invalid Android version: {version!r}")
           build_date = datetime.datetime.now(ZoneInfo("Asia/Shanghai")).strftime("%Y%m%d")
           # Match the dated release tags used by the desktop and iOS jobs.
-          if os.environ["GITHUB_REF_TYPE"] == "tag":
+          tag = os.environ.get("CROSSDESK_SOURCE_TAG")
+          if not tag and os.environ["GITHUB_REF_TYPE"] == "tag":
               tag = os.environ["GITHUB_REF_NAME"]
+          if tag:
+              tag = tag.removeprefix("android-")
               match = re.fullmatch(r"v?[0-9]+(?:\.[0-9]+){1,3}-(?:[0-9]+-)?([0-9]{8})(?:-[0-9]+)?", tag)
               if match:
                   build_date = match[1]
                   datetime.datetime.strptime(build_date, "%Y%m%d")
           version = f"v{version}-{build_date}"
+          source_tag = os.environ.get("CROSSDESK_SOURCE_TAG", "")
+          if source_tag.startswith("android-v") and source_tag.removeprefix("android-") != version:
+              raise ValueError(f"Android source tag does not match the app version: {source_tag} vs {version}")
           output = Path(os.environ["RUNNER_TEMP"]) / "crossdesk-android"
           for variant, source in (
               ("unsigned", "release/app-release-unsigned.apk"),