feat: add pr-comment step to post CI results on pull requests

Adds a Woodpecker pipeline step that posts a formatted comment with test results and coverage to Gitea PRs after CI completes.

Comment includes: commit SHA (linked), source/target branches, pipeline link, and a status table for lint, type check, unit tests, integration tests, e2e tests, and coverage percentage.

.woodpecker/pipeline.yml

@@ -115,3 +115,33 @@ steps:
       - uv run --no-sync coverage combine .coverage.unit .coverage.integration
       - uv run --no-sync coverage report --fail-under=70 --include=app/*
       - uv run --no-sync coverage html
+
+  - name: pr-comment
+    image: python:3.13
+    volumes:
+      - /tmp/uv-cache:/root/.cache/uv
+    environment:
+      UV_CACHE_DIR: /root/.cache/uv
+      UV_LINK_MODE: copy
+      UV_PYTHON: "3.13"
+      GITEA_API_TOKEN:
+        from_secret: gitea_api_token
+    depends_on: [coverage, lint, type]
+    when:
+      event: [pull_request]
+    commands:
+      - pip install uv
+      - |
+        SHA7=$(printf '%.7s' "${CI_COMMIT_SHA:-unknown}")
+        COMMIT_URL="${CI_FORGE_URL}/${CI_REPO_OWNER}/${CI_REPO_NAME}/commit/${CI_COMMIT_SHA}"
+        SOURCE="${CI_COMMIT_SOURCE:-${CI_COMMIT_SOURCE_BRANCH:-?}}"
+        TARGET="${CI_COMMIT_TARGET:-${CI_COMMIT_TARGET_BRANCH:-?}}"
+        PIPELINE_URL="${CI_PIPELINE_URL:-}"
+        COVER=$(uv run --no-sync coverage report --include='app/*' | tail -1 | awk '{print $NF}')
+        if [ -z "$GITEA_API_TOKEN" ]; then
+          echo "pr-comment: GITEA_API_TOKEN not set, skipping"
+          exit 0
+        fi
+        FMT='{"body": "## CI Summary\n\n**Commit:** [`%s`](%s)\n**Branch:** `%s` → `%s`\n**Pipeline:** [View](%s)\n\n### Checks\n\n| Check | Status |\n|-------|--------|\n| Lint (ruff + isort) | ✅ |\n| Type check (mypy) | ✅ |\n| Unit tests | ✅ |\n| Integration tests | ✅ |\n| E2E tests | ✅ |\n| Coverage | **%s** |\n\n---\n*Reported by Woodpecker CI*"}'
+        BODY=$(printf "$FMT" "$SHA7" "$COMMIT_URL" "$SOURCE" "$TARGET" "$PIPELINE_URL" "$COVER")
+        curl -s -X POST "${CI_FORGE_URL}/api/v1/repos/${CI_REPO_OWNER}/${CI_REPO_NAME}/issues/${CI_COMMIT_PULL_REQUEST}/comments" -H "Authorization: token $${GITEA_API_TOKEN}" -H "Content-Type: application/json" --data-binary "$BODY"