v1.10 - Fix JSX/TSX context-aware commenting + plugin vendor check

• Vendored nvim-ts-context-commentstring plugin for context-aware commenting in JSX/TSX files
• Added dependency to Comment.nvim for proper integration
• Added recursive check in check.ps1 to verify all referenced plugins are vendored
• Fixes silent failure when commenting inside JSX/TSX embedded languages

The new check in check.ps1 recursively scans all lua/*.lua files and verifies that any plugin reference (owner/name format) has a corresponding directory in vendor/plugins/. This prevents similar issues where a plugin is referenced but not vendored.

All tests pass:

• check.ps1: 35 OK / 0 MISS
• test/run.ps1: 10 passed, 0 failed