- Add version.txt (0.6.0) read by CMakeLists.txt so
esp_app_get_description()->version matches the release tag
- Log firmware version on boot: "v0.6.0 — Node ID: X"
- Remove stale Kconfig help text (said default 2.0, actual is 15.0)
Fixes the version mismatch reported in #354 where flashing v0.5.3
binaries showed v0.4.3 because PROJECT_VER was never set.
Co-Authored-By: claude-flow <ruv@ruv.net>