move to RAM build

.gitea/workflows/android.yml

@@ -7,6 +7,7 @@ on:
       - main
     paths:
       - ".gitea/workflows/android.yml"
+      - ".gitea/actions/prepare-ram-ci/**"
 
 env:
   # Change only this value to build another RustDesk tag/release.
@@ -20,9 +21,23 @@ env:
 jobs:
   build-android:
     name: Build RustDesk Android ARM64
-    runs-on: rustdesk-android
+    runs-on: ci-linux-builder
+
+    defaults:
+      run:
+        shell: bash
+
+    env:
+      NEXUS_CARGO_URL: ${{ secrets.NEXUS_CARGO_URL }}
+      NEXUS_MAVEN_URL: ${{ secrets.NEXUS_MAVEN_URL }}
 
     steps:
+      - name: Checkout CI repository
+        uses: actions/checkout@v4
+
+      - name: Prepare RAM CI environment
+        uses: ./.gitea/actions/prepare-ram-ci
+
       # -----------------------------------------------------------------------
       # RustDesk source
       # -----------------------------------------------------------------------
@@ -249,7 +264,13 @@ jobs:
               [ -n "${preferred}" ] &&
               [ "$(flutter_version "${preferred}")" = "${requested}" ]
             ); then
-              root="${preferred}"
+              # Flutter writes into its SDK cache and receives source patches.
+              # Copy the image SDK into RAM before using it.
+              root="${fallback}"
+              if [ ! -d "${root}" ]; then
+                mkdir -p "$(dirname "${root}")"
+                cp -a "${preferred}" "${root}"
+              fi
             else
               root="${fallback}"
 
@@ -397,8 +418,17 @@ jobs:
           echo
           echo "=== vcpkg ==="
 
-          test -n "${VCPKG_ROOT:-}"
-          test -d "${VCPKG_ROOT}/.git"
+          # Reuse the image checkout and prebuilt libraries in RAM when present.
+          image_vcpkg="${VCPKG_ROOT:-}"
+          export VCPKG_ROOT="${CI_ROOT}/vcpkg"
+          if [ ! -d "${VCPKG_ROOT}/.git" ]; then
+            if [ -n "${image_vcpkg}" ] && [ -d "${image_vcpkg}/.git" ]; then
+              cp -a "${image_vcpkg}" "${VCPKG_ROOT}"
+            else
+              git clone https://github.com/microsoft/vcpkg.git "${VCPKG_ROOT}"
+            fi
+          fi
+          echo "VCPKG_ROOT=${VCPKG_ROOT}" >> "${GITHUB_ENV}"
 
           current_vcpkg="$(
             git -C "${VCPKG_ROOT}" rev-parse HEAD