Improve Electron and Windows embedding support

[kgarg2468]

Summary

• import server plugins via pathToFileURL(...).href, which fixes dynamic import() on Windows filesystem paths
• add raw viewport coordinate clicks (x/y) to /tabs/:tabId/click for cross-origin iframe cases such as Turnstile
• expose coordinate click fields through the OpenClaw tool schema and OpenAPI spec

Addresses two self-contained items from #3348.

Testing

• npm run build (existing TypeScript errors remain, script still succeeds by design and copies plugin.js)
• NODE_OPTIONS='--experimental-vm-modules' npx jest --runInBand --forceExit tests/unit/plugins.test.js tests/unit/openapi.test.js tests/unit/screenshotToolResult.test.js
• npm rebuild better-sqlite3 && NODE_OPTIONS='--experimental-vm-modules' npx jest --config jest.config.e2e.cjs --runInBand --forceExit tests/e2e/formSubmission.test.js

[skyfallsin]

Closing to reduce duplicate implementations. The Windows dynamic-import fix (pathToFileURL) is already on current master and released in v1.13.0. For the remaining coordinate interaction use case, #3377 is the newer focused PR with a dedicated API, validation, OpenAPI generation, and E2E coverage. Thank you for identifying both Electron/Windows gaps.