feat(ci): add clippy lint step for Rust services

INF-05: New rust-ci.yml runs cargo clippy with -D warnings for both
chat-server and stream-server.

.github/workflows/rust-ci.yml

@@ -0,0 +1,35 @@
+name: Rust CI
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'veza-chat-server/**'
+      - 'veza-stream-server/**'
+  pull_request:
+    branches: [main]
+    paths:
+      - 'veza-chat-server/**'
+      - 'veza-stream-server/**'
+
+jobs:
+  clippy-chat:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+      - name: Clippy lint
+        run: cargo clippy -- -D warnings
+        working-directory: veza-chat-server
+
+  clippy-stream:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+      - name: Clippy lint
+        run: cargo clippy -- -D warnings
+        working-directory: veza-stream-server