All uncommitted work from ESP32 GDB stub development session.
Includes:
- GDB stub (uos_gdbstub.c/.h/_entry.S)
- Startup vector table rewrite
- ESP32 HAL integration files
- Boot chain design docs
- AGENTS.md absolute rules (commit before refactor, no unauthorized changes)
- All prior deepseek session work
This commit prevents further data loss. No claims of correctness.
