Fix CI: Install tauri-cli before building

The build job was failing because `cargo tauri` requires the Tauri CLI
to be installed first.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: ndbroadbent

.github/workflows/ci.yml

@@ -116,6 +116,9 @@ jobs:
       - name: Install dependencies
         run: bun install
 
+      - name: Install Tauri CLI
+        run: cargo install tauri-cli --locked
+
       - name: Build Tauri app
         run: cargo tauri build
         env: