feat: eliminate all 242 @ts-expect-error in muya/lib — full type safety

- Add module declarations for untyped deps (katex, prismjs, dompurify,
  turndown, joplin-turndown-plugin-gfm, mermaid, popper.js,
  element-resize-detector, *.png, *.svg) in vite-env.d.ts
- Define BlockRules/InlineRules interfaces for marked parser rule objects
- Fix contentState controllers: null checks, index signatures, proper casts
- Fix UI components: BaseScrollFloat render/getItemElement signatures,
  override keywords, module declarations
- Extract import.meta.glob to JS file for tsc compatibility
- 61 files changed, @ts-expect-error count: 242 → 0

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>