docs: add Claude Code Skills documentation

Add docs/en/contribution/Claude-Code-Skills.md covering:
- CLAUDE.md scope (project context for Claude Code)
- /new-plugin skill (scaffold new instrumentation plugins)
- /plugin-test skill (run CI tests locally)

Link from Developer.md.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: wu-sheng

docs/en/contribution/Claude-Code-Skills.md

@@ -0,0 +1,48 @@
+# Claude Code Skills
+
+This project includes [Claude Code](https://claude.com/claude-code) configuration to assist with development.
+
+## CLAUDE.md
+
+The `CLAUDE.md` file at the project root provides Claude Code with project context:
+
+- **Project structure** — module layout, key files and their purposes
+- **Plugin API** — span types, instrumentation patterns (method replacement, wrapt proxy, async wrappers, interceptors), tags, component IDs
+- **Context & Carrier API** — `get_context()` signatures, Carrier format, correlation API
+- **Plugin configuration options** — all `SW_AGENT_*` plugin settings
+- **Testing framework** — Docker-based integration tests, expected data format, test patterns
+- **Build commands** — `make env`, `make test`, `make lint`, `make doc-gen`, etc.
+- **CI pipeline** — GitHub Actions matrix, Python version coverage
+- **GitHub Actions allow list** — Apache enforces pinned SHAs for third-party actions
+- **Complete plugin inventory** — all 35 instrumentation plugins by category
+
+## Skills
+
+### `/new-plugin` — Scaffold a New Plugin
+
+Generates all files needed for a new instrumentation plugin:
+
+- **Plugin module** (`skywalking/plugins/sw_<name>.py`) with correct instrumentation pattern based on plugin type (HTTP entry/exit, database, cache, MQ, RPC)
+- **Component enum entry** in `skywalking/__init__.py`
+- **Test directory** (`tests/plugin/{data|http|web}/sw_<name>/`) with:
+  - Test file with parametrized versions
+  - Docker Compose configuration
+  - Provider and consumer services
+  - Expected span data YAML
+- Post-generation reminders (component-libraries.yml, UI logo, doc-gen, lint)
+
+Usage: `/new-plugin` and provide the library name, type, and versions to test.
+
+### `/plugin-test` — Run Plugin Tests Locally
+
+Runs the same tests that CI runs, but locally:
+
+- Builds Docker test images for specific Python versions
+- Runs unit tests (no Docker needed) or plugin integration tests
+- Maps plugin names to test paths
+- Supports testing across multiple Python versions by rebuilding the Docker image
+- Includes troubleshooting guidance for common failures (proxy issues, container debugging)
+
+Usage: `/plugin-test` and specify the scope (e.g., `flask`, `redis`, `unit`, `all`) and Python version.
+
+**Important**: If you have `http_proxy`/`https_proxy` set, clear them before running plugin tests — the test HTTP requests must reach Docker containers directly.

docs/en/contribution/Developer.md

@@ -49,3 +49,6 @@ automatically follow environment.
 
 # Next
 Refer to the [Plugin Development Guide](How-to-develop-plugin.md) to learn how to build a new plugin for a library.
+
+## Claude Code Skills
+This project includes Claude Code configuration for AI-assisted development. See [Claude Code Skills](Claude-Code-Skills.md) for available skills (`/new-plugin`, `/plugin-test`) and what `CLAUDE.md` covers.