docs: reorganize README and add bilingual SDK guides

[ZephyrKeXiner]

The root README now provides a concise project introduction and links to the detailed overview, installation instructions, SDK guides, and contribution guide. The original project details are preserved in docs/overview.md and docs/zh/overview.md, with a separate Chinese README under docs/zh/.

Adds Star History and contributor sections, bilingual contribution guidelines, and complete TypeScript plugin SDK documentation covering local installation, a working plugin tutorial, manifests, permissions, lifecycle, host APIs, Swift host integration, examples, and troubleshooting. Language links and relative paths are updated throughout.

Validation:

• Checked 154 local links and anchors across all 10 changed documents; git diff --check passed.
• npm run typecheck and npm test passed in sdks/typescript (2 SDK tests).
• Built and installed a local SDK archive, compiled all three documented TypeScript examples, and exercised initialization, host calls, valid/invalid greeting input, three simulated lever states, notifications, shutdown, and exit through an isolated JSON-RPC harness.
• Confirmed that the English and Chinese guides use matching code examples.