Merge #95: Add coverage CI workflow

b4092b6 fix: [#90] add SKIP_AI_ENFORCEMENT to coverage steps (copilot-swe-agent[bot])
7653193 fix: [#90] add explicit permissions to coverage workflow (copilot-swe-agent[bot])
5afe9f8 feat: [#90] add coverage CI workflow (copilot-swe-agent[bot])
213b269 Initial plan (copilot-swe-agent[bot])

Pull request description:

  - [x] Add `SKIP_AI_ENFORCEMENT: 1` environment variable to coverage steps
  - [x] Applied to both `coverage-text` and `coverage-html` steps
  - [x] Matches pattern from `testing.yml` workflow
  - [x] Skips AI enforcement tests that require third-party tools (cargo machete, Ansible, OpenTofu)
  - [x] YAML linting passes

  <!-- START COPILOT CODING AGENT SUFFIX -->

  <details>

  <summary>Original prompt</summary>

  >
  > ----
  >
  > *This section details on the original issue you should resolve*
  >
  > <issue_title>Create coverage CI workflow</issue_title>
  > <issue_description>**Parent Epic**: #85
  >
  > ## Overview
  >
  > Create a GitHub Actions workflow to generate code coverage reports on every push and pull request. The workflow generates coverage in two formats: a text summary for immediate viewing in the workflow output, and an HTML report uploaded as an artifact for detailed inspection.
  >
  > **Note**: This issue does NOT include Codecov or other external coverage service integration.
  >
  > ## Goals
  >
  > - [ ] Generate coverage reports automatically in CI/CD for all branches
  > - [ ] Display coverage summary in workflow output (text format)
  > - [ ] Make detailed HTML coverage reports available as artifacts
  > - [ ] Add `.coverage/` directory to `.gitignore`
  >
  > ## Specifications
  >
  > ### Workflow Structure
  >
  > **Trigger Events**: Push and pull_request (following `testing.yml` pattern)
  >
  > **Job**: Single `coverage` job with these steps:
  >
  > 1. Checkout code - `actions/checkout@v4`
  > 2. Setup Rust toolchain - `dtolnay/rust-toolchain@stable`
  > 3. Enable caching - `Swatinem/rust-cache@v2`
  > 4. Install cargo-llvm-cov - `taiki-e/install-action@v2`
  > 5. Generate text coverage - `cargo cov`
  > 6. Generate HTML report - `cargo cov-html`
  > 7. Upload HTML artifact - `actions/upload-artifact@v4`
  >
  > ### Example Workflow
  >
  > ```yaml
  > name: Coverage
  >
  > on:
  >   push:
  >   pull_request:
  >
  > env:
  >   CARGO_TERM_COLOR: always
  >
  > jobs:
  >   coverage:
  >     name: Coverage Report
  >     runs-on: ubuntu-latest
  >
  >     steps:
  >       - id: checkout
  >         name: Checkout Repository
  >         uses: actions/checkout@v4
  >
  >       - id: setup
  >         name: Setup Toolchain
  >         uses: dtolnay/rust-toolchain@stable
  >
  >       - id: cache
  >         name: Enable Workflow Cache
  >         uses: Swatinem/rust-cache@v2
  >
  >       - id: install-llvm-cov
  >         name: Install cargo-llvm-cov
  >         uses: taiki-e/install-action@v2
  >         with:
  >           tool: cargo-llvm-cov
  >
  >       - id: coverage-text
  >         name: Generate Text Coverage Summary
  >         run: cargo cov
  >
  >       - id: coverage-html
  >         name: Generate HTML Coverage Report
  >         run: cargo cov-html
  >
  >       - id: upload-coverage
  >         name: Upload HTML Coverage Report
  >         uses: actions/upload-artifact@v4
  >         with:
  >           name: coverage-html-report
  >           path: target/llvm-cov/html/
  >           retention-days: 30
  > ```
  >
  > ## Implementation Plan
  >
  > ### Phase 1: Update .gitignore (5 minutes)
  >
  > - [ ] Add `.coverage/` directory to `.gitignore` with comment
  >
  > ### Phase 2: Create Workflow (15 minutes)
  >
  > - [ ] Create `.github/workflows/coverage.yml`
  > - [ ] Add trigger events and environment variables
  > - [ ] Set up job structure
  >
  > ### Phase 3: Configure Toolchain (10 minutes)
  >
  > - [ ] Add Rust toolchain setup, caching, and cargo-llvm-cov installation
  >
  > ### Phase 4: Generate Reports (15 minutes)
  >
  > - [ ] Add text and HTML coverage generation steps
  >
  > ### Phase 5: Upload Artifact (10 minutes)
  >
  > - [ ] Add artifact upload step with 30-day retention
  >
  > ### Phase 6: Testing (15 minutes)
  >
  > - [ ] Test workflow on a feature branch
  > - [ ] Verify text output and HTML artifact availability
  >
  > ## Acceptance Criteria
  >
  > - [ ] `.coverage/` directory added to `.gitignore`
  > - [ ] Workflow file exists at `.github/workflows/coverage.yml`
  > - [ ] Workflow triggers on push and pull_request
  > - [ ] Text coverage summary visible in workflow output
  > - [ ] HTML coverage artifact uploaded with 30-day retention
  > - [ ] Workflow does NOT block CI/CD on coverage failures
  >
  > ## Notes
  >
  > - Uses `cov` and `cov-html` aliases from `.cargo/config.toml`
  > - Follows patterns from existing `testing.yml` workflow
  > - Non-blocking by design - coverage is informational only
  > - Future enhancement: External coverage service integration can be added later</issue_description>
  >
  > ## Comments on the Issue (you are @copilot in this section)
  >
  > <comments>
  > </comments>
  >

  </details>

  - Fixes #87

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ACKs for top commit:
  josecelano:
    ACK b4092b6

Tree-SHA512: f5ee09387a3b4de3183ec90dcccebe771b8925722be123dd1715bfdb6fa3058fa5958548a2893ead822256cd33879e69438e59165866a50736a18123569c44d4

Author: josecelano

.github/workflows/coverage.yml

@@ -0,0 +1,55 @@
+name: Coverage
+
+on:
+  push:
+  pull_request:
+
+env:
+  CARGO_TERM_COLOR: always
+
+permissions:
+  contents: read
+
+jobs:
+  coverage:
+    name: Coverage Report
+    runs-on: ubuntu-latest
+
+    steps:
+      - id: checkout
+        name: Checkout Repository
+        uses: actions/checkout@v4
+
+      - id: setup
+        name: Setup Toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      - id: cache
+        name: Enable Workflow Cache
+        uses: Swatinem/rust-cache@v2
+
+      - id: install-llvm-cov
+        name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@v2
+        with:
+          tool: cargo-llvm-cov
+
+      - id: coverage-text
+        name: Generate Text Coverage Summary
+        env:
+          SKIP_AI_ENFORCEMENT: 1
+        run: cargo cov
+
+      - id: coverage-html
+        name: Generate HTML Coverage Report
+        env:
+          SKIP_AI_ENFORCEMENT: 1
+        run: cargo cov-html
+
+      - id: upload-coverage
+        name: Upload HTML Coverage Report
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-html-report
+          path: target/llvm-cov/html/
+          retention-days: 30