Rename internal tinymce type aliases and the TinyMCE.ts / getTinymce helper

[curdopet]

Context

This package is a React wrapper for OpenTiny, not TinyMCE, but many internal identifiers still refer to tinymce/TinyMCE (leftovers from the @tinymce/tinymce-react fork). These should be renamed to reflect OpenTiny. This issue covers the pure, non-breaking internal renames.

Scope

• Rename type aliases TinyMCEEditor → OpenTinyEditor and TinyMCEGlobal → OpenTinyGlobal:
  • src/main/ts/Events.ts, src/main/ts/Utils.ts, src/main/ts/components/Editor.tsx, src/main/ts/TinyMCE.ts
  • src/test/ts/alien/TestHelpers.ts, src/test/ts/alien/Loader.tsx, src/test/ts/browser/EditorBehaviorTest.ts, src/stories/Editor.stories.tsx
• Rename the file src/main/ts/TinyMCE.ts → OpenTiny.ts and update its imports (src/main/ts/components/Editor.tsx, src/test/ts/browser/EditorBehaviorTest.ts).
• Rename the getTinymce helper → getOpenTiny (the function still reads the window.tinymce global internally, keep that).
• Rename test file src/test/ts/browser/LoadTinyTest.ts → LoadOpenTinyTest.ts and its local helpers (cDeleteTinymce, hasTinymceUri).

Out of scope

Kept for compatibility: the window.tinymce runtime global, the public tinymceScriptSrc prop, and the tinymce.min.js bundle filename.