fix(ci): replace GitHub Actions with Forgejo-compatible workflow

The original workflow was using GitHub-specific actions that don't exist
in Forgejo, causing CI to fail immediately with:
  'repository not found: Not Found' for actions-rs/toolchain@v1

Key changes:
- Replace 'runs-on: docker' with 'runs-on: ubuntu-latest' and proper containers
- Remove 'actions-rs/toolchain@v1' (doesn't exist in Forgejo)
  - Use 'rust:latest' container image instead which includes rustfmt, clippy, and cargo
- Update all action references to use full URLs (https://github.com/...)
- Use 'docker:dind' service for Docker-in-Docker support
- Remove 'docker/setup-buildx-action@v3' (not needed for basic docker build)

This workflow is now compatible with Forgejo and should run successfully.

.forgejo/workflows/lint-and-build.yml

@@ -17,33 +17,27 @@ env:
 jobs:
   lint:
     name: Lint
-    runs-on: docker
+    runs-on: ubuntu-latest
+    container:
+      image: rust:latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
-
-      - name: Install Rust toolchain
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          components: rustfmt, clippy
-          override: true
+        uses: https://github.com/actions/checkout@v4
 
       - name: Cache cargo registry
-        uses: actions/cache@v3
+        uses: https://github.com/actions/cache@v3
         with:
           path: ~/.cargo/registry
           key: ${{ runner.os }}-cargo-registry-${{ hashFiles('**/Cargo.lock') }}
 
       - name: Cache cargo index
-        uses: actions/cache@v3
+        uses: https://github.com/actions/cache@v3
         with:
           path: ~/.cargo/git
           key: ${{ runner.os }}-cargo-index-${{ hashFiles('**/Cargo.lock') }}
 
       - name: Cache cargo build
-        uses: actions/cache@v3
+        uses: https://github.com/actions/cache@v3
         with:
           path: backend/target
           key: ${{ runner.os }}-cargo-build-target-${{ hashFiles('**/Cargo.lock') }}
@@ -60,33 +54,28 @@ jobs:
 
   build:
     name: Build
-    runs-on: docker
+    runs-on: ubuntu-latest
+    container:
+      image: rust:latest
     needs: lint
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
-
-      - name: Install Rust toolchain
-        uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
+        uses: https://github.com/actions/checkout@v4
 
       - name: Cache cargo registry
-        uses: actions/cache@v3
+        uses: https://github.com/actions/cache@v3
         with:
           path: ~/.cargo/registry
           key: ${{ runner.os }}-cargo-registry-${{ hashFiles('**/Cargo.lock') }}
 
       - name: Cache cargo index
-        uses: actions/cache@v3
+        uses: https://github.com/actions/cache@v3
         with:
           path: ~/.cargo/git
           key: ${{ runner.os }}-cargo-index-${{ hashFiles('**/Cargo.lock') }}
 
       - name: Cache cargo build
-        uses: actions/cache@v3
+        uses: https://github.com/actions/cache@v3
         with:
           path: backend/target
           key: ${{ runner.os }}-cargo-build-target-${{ hashFiles('**/Cargo.lock') }}
@@ -103,14 +92,16 @@ jobs:
 
   docker-build:
     name: Docker Build
-    runs-on: docker
+    runs-on: ubuntu-latest
+    container:
+      image: docker:latest
     needs: build
+    services:
+      docker:
+        image: docker:dind
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
-
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: https://github.com/actions/checkout@v4
 
       - name: Build Docker image
         working-directory: ./backend