ci: cache cargo registry + lsposed/native target

The zygisk job has had this for a while; lsposed/native was rebuilding
the uniffi/serde/quinn deps from scratch every run. Same shape as the
zygisk cache, separate cache key so the two jobs don't fight over a
shared `target/` (different crate, different artifacts).

.github/workflows/ci.yml

@@ -181,6 +181,16 @@ jobs:
       - name: Mark workspace safe
         run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
 
+      - name: Cache cargo
+        uses: actions/cache@v5
+        with:
+          path: |
+            /usr/local/cargo/registry
+            /usr/local/cargo/git
+            lsposed/native/target
+          key: cargo-${{ runner.os }}-lsposed-${{ hashFiles('lsposed/native/Cargo.lock') }}
+          restore-keys: cargo-${{ runner.os }}-lsposed-
+
       - name: Set up keystore
         env:
           KEYSTORE_BASE64: ${{ secrets.ANDROID_KEYSTORE_BASE64 }}