Remove tar actions/cache in setup-flutter in favor of instant persistent disk SDK reuse

setup-flutter/action.yml

@@ -1,5 +1,5 @@
 name: 'Setup Flutter'
-description: 'Cross-platform setup for Flutter with caching on macOS, Windows, and Linux.'
+description: 'Cross-platform setup for Flutter with local mirror and multi-runner concurrency support.'
 inputs:
   version:
     description: 'Flutter channel, version tag, or commit hash (e.g., master, stable, 3.29.0, 4ebf37fe7df0a130ba5bee17315b98f905c10b34)'
@@ -13,10 +13,6 @@ inputs:
     description: 'Gitea token for authenticated git cloning'
     required: false
     default: ''
-  cache:
-    description: 'Enable Flutter SDK caching'
-    required: false
-    default: 'true'
   enable_windowing:
     description: 'Enable windowing and desktop support'
     required: false
@@ -25,24 +21,8 @@ inputs:
 runs:
   using: 'composite'
   steps:
-    - name: Determine Cache Key
-      id: cache-key
-      shell: bash
-      run: |
-        echo "key=flutter-${{ runner.os }}-${{ runner.arch }}-${{ inputs.version }}" >> $GITHUB_OUTPUT
-
-    - name: Cache Flutter SDK
-      if: inputs.cache == 'true'
-      id: flutter-cache
-      uses: actions/cache@v3
-      with:
-        path: |
-          ~/flutter-sdk
-          C:\flutter-sdk
-        key: ${{ steps.cache-key.outputs.key }}
-
     - name: Install Flutter (macOS / Linux)
-      if: runner.os != 'Windows' && steps.flutter-cache.outputs.cache-hit != 'true'
+      if: runner.os != 'Windows'
       shell: bash
       run: |
         LOCK_DIR="${TMPDIR:-/tmp}/flutter-sdk-setup.lock"
@@ -82,7 +62,7 @@ runs:
         rm -rf "$LOCK_DIR" || true
 
     - name: Install Flutter (Windows)
-      if: runner.os == 'Windows' && steps.flutter-cache.outputs.cache-hit != 'true'
+      if: runner.os == 'Windows'
       shell: powershell
       run: |
         $lockDir = Join-Path $env:TEMP "flutter-sdk-setup.lock"