Major cleanup: Remove unused files and organize documentation

Deleted unused 'simple*' files:
- src/simpleBackground.js (NOT used - manifest uses background.js)
- src/simpleContent.js (NOT used - manifest uses content.js)
- All simpleContent backup files (_restored, _working)
- Entire dist/ folder (old build artifacts, not needed)

Organized documentation:
- Created docs/ folder
- Moved all 23 .md files to docs/
- Cleaner project root directory

Result:
- Removed 1,753+ lines of dead code
- Eliminated confusion about which files are active
- Only manifest.json-loaded files remain in src/
- Much cleaner codebase structure

Active files:
✅ background.js (service worker)
✅ content.js (content script)
✅ All files in manifest.json

Author: rainerstudios