fix(make-pdf): replace regex sanitizer with parser-backed sanitization

[arpitjain099]

Summary

• replace make-pdf's regex-based HTML sanitizer with sanitize-html to reduce bypass risk from malformed-but-browser-accepted markup
• keep markdown-oriented tags while dropping active/embed surfaces (scripts, iframes, forms, event handlers, javascript: URLs)
• update sanitizer unit tests to reflect stricter URL/SVG handling and keep existing coverage passing

Why

Code scanning flags the previous regex approach as incomplete tag/attribute sanitization. A parser-backed sanitizer is more robust and easier to reason about for untrusted markdown-to-HTML conversion.

Verification

• bun test make-pdf/test/render.test.ts
• bun test make-pdf/test/

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