ci: install Tauri/GTK Linux dev libs so the Rust workspace test compiles

`wifi-densepose-desktop` is a Tauri v2 app and pulls glib-sys / gtk-sys /
webkit2gtk-sys / libsoup-sys via its (build-)dependencies. Those crates'
build.rs uses pkg-config, which needs the matching `-dev` packages on the
runner — without them the build aborts at `glib-sys` long before any test
runs ("pkg-config exited with status code 1: glib-2.0 not found"). Every
recent CI run on main has been red on this exact step (last green Rust
workspace test predates the Tauri 2 desktop crate).

Install the standard Tauri-on-Ubuntu set in the Rust tests job so the
workspace test can actually exercise the workspace (the binary itself isn't
built into a release here — these are just the libraries `pkg-config --cflags`
needs to see).

Co-Authored-By: claude-flow <ruv@ruv.net>

.github/workflows/ci.yml

@@ -70,6 +70,26 @@ jobs:
     - name: Checkout code
       uses: actions/checkout@v4
 
+    # `wifi-densepose-desktop` is a Tauri v2 app — `glib-sys`, `gtk-sys`,
+    # `webkit2gtk-sys`, etc. need the Linux dev libraries via pkg-config or the
+    # workspace test fails at the build step before any test runs (every recent
+    # main CI run has been red on this for exactly this reason). Install the
+    # standard Tauri-on-Ubuntu set.
+    - name: Install Tauri / GTK system dev libraries
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y --no-install-recommends \
+          libglib2.0-dev \
+          libgtk-3-dev \
+          libsoup-3.0-dev \
+          libjavascriptcoregtk-4.1-dev \
+          libwebkit2gtk-4.1-dev \
+          libayatana-appindicator3-dev \
+          librsvg2-dev \
+          libxdo-dev \
+          libssl-dev \
+          pkg-config
+
     - name: Install Rust toolchain
       uses: dtolnay/rust-toolchain@stable