perf: use Swatinem/rust-cache for faster builds

Replace manual cache config with rust-cache action which:
- Caches ~/.cargo registry, index, and git data
- Caches target directory with incremental compilation
- cache-all-crates: ensures all dependencies are cached
- cache-on-failure: saves cache even if build fails

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

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

Author: zcg

.github/workflows/88code-release.yml

@@ -67,15 +67,14 @@ jobs:
         with:
           targets: ${{ matrix.target }}
 
-      - uses: actions/cache@v4
+      - name: Cache Rust dependencies
+        uses: Swatinem/rust-cache@v2
         with:
-          path: |
-            ~/.cargo/bin/
-            ~/.cargo/registry/index/
-            ~/.cargo/registry/cache/
-            ~/.cargo/git/db/
-            ${{ github.workspace }}/codex-rs/target/
-          key: cargo-${{ matrix.runner }}-${{ matrix.target }}-release-${{ hashFiles('**/Cargo.lock') }}
+          workspaces: codex-rs -> target
+          shared-key: ${{ matrix.target }}
+          save-if: ${{ github.ref == 'refs/heads/main' }}
+          cache-on-failure: true
+          cache-all-crates: true
 
       - name: Install musl tools (Linux)
         if: contains(matrix.target, 'musl')