Add Gitea Action to build app for Linux and Windows

Triggers on pushes to app/ directory. Builds Tauri app on both
platforms with Rust caching, uploads .AppImage/.deb/.rpm for Linux
and .msi/.exe for Windows as artifacts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitea/workflows/build-app.yml

@@ -0,0 +1,113 @@
+name: Build App
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - "app/**"
+      - ".gitea/workflows/build-app.yml"
+  pull_request:
+    branches: [main]
+    paths:
+      - "app/**"
+  workflow_dispatch:
+
+jobs:
+  build-linux:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            libgtk-3-dev \
+            libwebkit2gtk-4.1-dev \
+            libayatana-appindicator3-dev \
+            librsvg2-dev \
+            libsoup-3.0-dev \
+            libssl-dev \
+            libxdo-dev \
+            patchelf \
+            pkg-config \
+            build-essential \
+            curl \
+            wget \
+            file
+
+      - name: Install Rust stable
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Rust cache
+        uses: swatinem/rust-cache@v2
+        with:
+          workspaces: "./app/src-tauri -> target"
+
+      - name: Install Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+
+      - name: Install frontend dependencies
+        working-directory: ./app
+        run: npm ci
+
+      - name: Install Tauri CLI
+        working-directory: ./app
+        run: npx tauri --version || npm install @tauri-apps/cli
+
+      - name: Build Tauri app
+        working-directory: ./app
+        run: npx tauri build
+
+      - name: Upload Linux artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: triple-c-linux
+          path: |
+            app/src-tauri/target/release/bundle/appimage/*.AppImage
+            app/src-tauri/target/release/bundle/deb/*.deb
+            app/src-tauri/target/release/bundle/rpm/*.rpm
+          if-no-files-found: warn
+
+  build-windows:
+    runs-on: windows-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust stable
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Rust cache
+        uses: swatinem/rust-cache@v2
+        with:
+          workspaces: "./app/src-tauri -> target"
+
+      - name: Install Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+
+      - name: Install frontend dependencies
+        working-directory: ./app
+        run: npm ci
+
+      - name: Install Tauri CLI
+        working-directory: ./app
+        run: npx tauri --version || npm install @tauri-apps/cli
+
+      - name: Build Tauri app
+        working-directory: ./app
+        run: npx tauri build
+
+      - name: Upload Windows artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: triple-c-windows
+          path: |
+            app/src-tauri/target/release/bundle/msi/*.msi
+            app/src-tauri/target/release/bundle/nsis/*.exe
+          if-no-files-found: warn