docs(release): update README and CHANGELOG for v4.1.0 release

- Add comprehensive v4.1.0 section to README with RTOS transformation details
- Document all changes since v4.0.0 including phases 6-8
- Add performance comparison table showing 500× improvements
- Include LED enhancements (60 FPS, 10 states, 5 patterns)
- Document testing suite (59 tests, ~90% coverage)
- Add comprehensive RTOS documentation section (~5000 lines)
- Update CHANGELOG with detailed v4.1.0 entry covering:
  * RTOS Core Infrastructure (Issue #13)
  * Command Task (Issue #14)
  * WiFi Task (Issue #15)
  * Web Server Task (Issue #16)
  * Analysis Task (Issue #17)
  * LED Task Enhancement (Issue #18)
  * Testing Suite (Issue #19)
  * Documentation Suite (Issue #20)
- Version bumped to 4.1.0 via version-manager script

Author: arunkumar-mourougappane