Upgrade project toolchain and dependencies

[ruibaby]

Upgrade the project toolchain using create-halo-plugin as a reference.

• Upgrade the Lombok plugin to 9.2.0 and regenerate the Gradle 9.5.0 wrapper.
• Align root and UI TypeScript versions on 6.0 and update Vue tooling and Node.js types.
• Include the example's Vite declarations and update ALTCHA test mocks for TypeScript 6 compatibility.
• Pin Gradle's pnpm setup to 12.4.2, explicitly select Java 21 in CI/CD, and update npm release actions.
• Document development prerequisites.

Validation:

• Gradle clean build passed with Java 21, including 196 backend tests.
• Comment widget tests passed: 128 tests, including browser tests.
• UI tests passed: 2 tests; widget chunk invalidation test passed.
• UI, comment widget, and example type checks passed.
• Frozen-lockfile installation and targeted Biome checks passed.
• Verified that the plugin JAR contains UI and widget assets.

Halo DevTools still emits a Gradle 10 deprecation warning for execution-time Task.project access.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-20T09:04:35.071158Z	509e354	PR opened

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