docs: satellite development workflow (pnpm link + hot reload + release flow)

[tomymaritano]

Context

Cross-repo iteration friction is the real cost of satellites-now for a 2-person team. The mitigation is a documented, tested workflow.

Acceptance criteria

• CONTRIBUTING in plugin-template (copied to each satellite): clone app + satellite, pnpm link, hot-reload loop (pluginRuntimeStore watcher), test against local app, publish via tag
• Verified end-to-end by extracting plugin-word-count following ONLY the doc
• Troubleshooting: version skew vs @dripnex/plugin-api, native-deps rule (never in plugins)