made a better image, now node and flutter are included.

.docker/Dockerfile

@@ -0,0 +1,35 @@
+FROM ubuntu:22.04
+
+# Set environment variables
+ENV FLUTTER_HOME=/opt/flutter
+ENV PATH="$FLUTTER_HOME/bin:$PATH"
+ENV PUB_CACHE=/opt/pub-cache
+
+# Install system dependencies including Node.js
+# Nodejs is required for the forgejo runner (checkout action)
+RUN apt-get update && apt-get install -y \
+    curl \
+    git \
+    wget \
+    unzip \
+    ca-certificates \
+    gnupg \
+    && mkdir -p /etc/apt/keyrings \
+    && curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg \
+    && echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_20.x nodistro main" | tee /etc/apt/sources.list.d/nodesource.list \
+    && apt-get update \
+    && apt-get install -y nodejs \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Flutter
+RUN git clone https://github.com/flutter/flutter.git $FLUTTER_HOME \
+    && flutter doctor \
+    && flutter channel stable \
+    && flutter upgrade \
+    && flutter config --enable-web \
+    && flutter precache --web
+
+# Create cache directories
+RUN mkdir -p $PUB_CACHE
+
+WORKDIR /workspace

.forgejo/workflows/main-build.yaml

@@ -5,37 +5,34 @@ on:
 
 jobs:
   build-web:
+    # custom runner image -> includes node and latest flutter stable
     runs-on: flutter-web-builder
     steps:
-      - name: install node
-        id: node-install
-        run: | 
-          apt update
-          apt install -y ca-certificates curl gnupg
-          mkdir -p /etc/apt/keyrings
-          curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg
-          echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_20.x nodistro main" | tee /etc/apt/sources.list.d/nodesource.list
-          apt update
-          apt install -y nodejs
-          flutter channel stable
-          flutter upgrade
-
       - name: Checkout code
         uses: actions/checkout@v4
 
-      - name: Cache Flutter
+      # Cache pub dependencies (this should work now)
-        id: cache-flutter
-        uses: actions/cache@v4
-        with:
-          path: ${{ forge.workspace }}/../.tool-cache
-          key: ${{ forge.ref_name }}-flutter-cache-temp
-
       - name: Cache pub dependencies
         uses: actions/cache@v4
         id: cache-pub
         with:
-          path: ${{ forge.workspace }}/../.pub-cache
+          path: /opt/pub-cache
-          key: ${{ forge.ref_name }}-pub-cache-temp
+          key: ${{ runner.os }}-pub-${{ hashFiles('**/pubspec.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-pub-
+
+      # Cache build outputs and tool cache
+      - name: Cache Flutter build
+        uses: actions/cache@v4
+        with:
+          path: |
+            .dart_tool
+            build
+          key: ${{ runner.os }}-flutter-build-${{ hashFiles('**/pubspec.lock') }}-${{ hashFiles('lib/**/*.dart') }}
+          restore-keys: |
+            ${{ runner.os }}-flutter-build-${{ hashFiles('**/pubspec.lock') }}-
+            ${{ runner.os }}-flutter-build-
+
       - name: Get dependencies
         run: flutter pub get