ci: add Gitea Actions workflows for Linux-only CI and release

Adapt GitHub Actions workflows for Gitea with Docker runner:
- Linux-only builds (no macOS/Windows matrix)
- Manual `npm run tauri build` instead of tauri-action
- Release creation via Gitea API with asset upload

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build.yml

@@ -0,0 +1,91 @@
+name: CI
+
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+    branches: [main, master]
+
+concurrency:
+  group: ${{ gitea.workflow }}-${{ gitea.ref }}
+  cancel-in-progress: true
+
+jobs:
+  lint-and-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Linux dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libgtk-3-dev libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy, rustfmt
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: src-tauri
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+
+      - name: Install frontend dependencies
+        run: npm ci
+
+      - name: ESLint
+        run: npm run lint
+
+      - name: Rust fmt check
+        run: cd src-tauri && cargo fmt --check
+
+      - name: Rust clippy
+        run: cd src-tauri && cargo clippy -- -D warnings
+
+      - name: Rust tests
+        run: cd src-tauri && cargo test
+
+      - name: Frontend tests
+        run: npm test
+
+  build:
+    needs: lint-and-test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Linux dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libgtk-3-dev libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev
+
+      - uses: dtolnay/rust-toolchain@stable
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: src-tauri
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+
+      - name: Install frontend dependencies
+        run: npm ci
+
+      - name: Build Tauri app
+        run: npm run tauri build
+
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: tusk-linux-x64
+          path: |
+            src-tauri/target/release/bundle/deb/*.deb
+            src-tauri/target/release/bundle/rpm/*.rpm
+            src-tauri/target/release/bundle/appimage/*.AppImage
+          if-no-files-found: ignore