docs: advanced media processing evidence package

  Complete evidence package for Sia Foundation Grant Milestone 5:
  - Comprehensive evidence document (15K+ words)
  - Interactive progressive rendering demo (HTML)
  - One-command launch script (run-demo.sh)
  - Testing and validation guide
  - Browser compatibility verified (Chrome, Edge, Firefox - Oct 23, 2025)

  Deliverables:
  ✅ JPEG/PNG/WebP thumbnails (≤64 KB average)
  ✅ Progressive rendering (3 strategies - tested in 3 browsers)
  ✅ Browser test matrix (85% market share coverage)
  ✅ Bundle size: 60.09 KB (10x under 700 KB requirement)

  Test Results:
  - 437 total tests passing
  - 225+ media-specific tests
  - Real S5 network integration validated
  - Cross-browser demo verified (Chrome, Edge, Firefox)

  Browser Testing (October 23, 2025):
  - Google Chrome: ✅ All strategies working perfectly
  - Microsoft Edge: ✅ All strategies working perfectly
  - Mozilla Firefox: ✅ All strategies working perfectly
  - Coverage: 85% desktop market share

Author: Developer