ci: add PR cargo check workflow

Runs cargo check for both crates on every pull request:
- blxcode (Tauri backend, native Linux)
- blxcode-ui (Leptos frontend, wasm32-unknown-unknown)

Uses dtolnay/rust-toolchain for reliable toolchain setup
and actions/cache to speed up repeated runs.

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

Author: Maik Roland Damm

.github/workflows/pr-check.yml

@@ -0,0 +1,45 @@
+name: PR Check
+
+on:
+  pull_request:
+
+jobs:
+  cargo-check:
+    name: cargo check
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust stable
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: wasm32-unknown-unknown
+
+      - name: Cache cargo registry + build
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry/index
+            ~/.cargo/registry/cache
+            ~/.cargo/git/db
+            target
+          key: ${{ runner.os }}-cargo-check-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: ${{ runner.os }}-cargo-check-
+
+      - name: Install Linux system deps (for cpal / Tauri)
+        run: |
+          sudo apt-get update -qq
+          sudo apt-get install -y --no-install-recommends \
+            libasound2-dev \
+            libgtk-3-dev \
+            libwebkit2gtk-4.1-dev \
+            libappindicator3-dev \
+            librsvg2-dev \
+            patchelf
+
+      - name: Check backend (blxcode)
+        run: cargo check -p blxcode
+
+      - name: Check frontend (blxcode-ui, WASM)
+        run: cargo check -p blxcode-ui --target wasm32-unknown-unknown