feat: Add HarmonyOS support for .ets files and review configurations

[stay-foolish-forever]

Description

Add complete HarmonyOS/ArkTS development support to OCR's review capabilities.

HarmonyOS uses .ets (ArkTS) source files and .json5 configuration files (module.json5, app.json5, oh-package.json5). This PR enables OCR to review these file types with dedicated rules, while properly excluding dependency directories and test files.

Changes:

• Add .ets and .json5 to the supported file types allowlist
• Create arkts.md rule doc covering ArkTS-specific checks (state decorators, lifecycle, declarative UI, performance, resource access, component communication) plus TypeScript general checks
• Map **/.ets → arkts.md and **/.json5 → json.md in system_rules.json
• Exclude /oh_modules/ (HarmonyOS dependency directory) and **/*.test.ets (test files) from review
• Add unit tests for all new extensions and patterns

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring (no functional changes)
• Documentation update
• CI / Build / Tooling

How Has This Been Tested?

• make test passes locally
• Manual testing (describe below)

Checklist

• My code follows the project's coding style (go fmt, go vet)
• I have performed a self-review of my code
• I have added tests that prove my fix is effective or my feature works
• New and existing unit tests pass locally with my changes
• I have updated the documentation accordingly (if applicable)
• I have signed the CLA

Related Issues

Issue #47