chore: import upstream snapshot with attribution

.github/workflows/coverage.yml

@@ -0,0 +1,54 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: Coverage
+
+on:
+  push:
+    branches: [main]
+    paths: ['**/*.rs', 'Cargo.toml', 'Cargo.lock']
+  pull_request:
+    branches: [main]
+    paths: ['**/*.rs', 'Cargo.toml', 'Cargo.lock']
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
+
+jobs:
+  coverage:
+    name: Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+      
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@631a55b12751854ce901bb631d5902ceb48146f7 # stable
+        with:
+          components: llvm-tools-preview
+          
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@a37010ded18ff788be4440302bd6830b1ae50d8b # cargo-llvm-cov
+        with:
+          tool: cargo-llvm-cov
+        
+      - name: Generate code coverage
+        run: cargo llvm-cov --all-features --workspace --lcov --output-path lcov.info
+        
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@b9fd7d16f6d7d1b5d2bec1a2887e65ceed900238 # v4
+        with:
+          files: lcov.info
+          fail_ci_if_error: false
+          token: ${{ secrets.CODECOV_TOKEN }}