Bring cloud sync and the web beta into main

.github/actions/setup-flutter/action.yml

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+name: Set up Flutter
+description: >-
+  Install the Flutter SDK pinned in .fvmrc through FVM, reusing cached pub
+  packages and SDKs, then fetch the app's dependencies. Expects FVM_HOME and
+  PUB_CACHE in the job environment.
+
+runs:
+  using: composite
+  steps:
+    # Its problem matcher resolves against the calling action's folder and
+    # fails inside a composite action, so it stays off.
+    - uses: dart-lang/setup-dart@v1
+      with:
+        problem-matcher: false
+
+    - name: Cache Pub Packages
+      uses: actions/cache@v4
+      with:
+        path: .pub-cache
+        key: ${{ runner.os }}-pub-${{ hashFiles('**/pubspec.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-pub-
+
+    - name: Cache FVM SDK
+      uses: actions/cache@v4
+      with:
+        path: .fvm_cache
+        key: ${{ runner.os }}-fvm-${{ hashFiles('.fvmrc') }}
+        restore-keys: |
+          ${{ runner.os }}-fvm-
+
+    # pwsh runs on every runner OS, and calls fvm.bat on Windows correctly.
+    - name: Add Pub Cache To PATH
+      shell: pwsh
+      run: Join-Path $env:PUB_CACHE "bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+
+    - name: Install FVM
+      shell: pwsh
+      run: dart pub global activate fvm
+
+    - name: Install Flutter SDK
+      shell: pwsh
+      run: fvm install
+
+    - name: Get Dependencies
+      shell: pwsh
+      run: fvm flutter pub get