feat(tools): integration of automated firmware flashing and protocol testing

[q23818]

This PR integrates automated firmware deployment with physical hardware protocol validation for the ESP32-C3 chassis controller, resolving dynamic port mapping limitations on macOS/Linux hosts and establishing an unattended flashing-to-testing pipeline.

Issues Addressed & Solutions

1. Host Serial Port Hardcoding

   • Problem: tests/test_uart.py previously hardcoded /dev/ttyS1, causing immediate connection failures on macOS targets.
   • Solution: Replaced static configuration with argparse to allow dynamic runtime port injection (e.g., /dev/cu.usbmodem*).
   • Addition: Added active buffer clearance and an explicit CMD_RESET guard in the connection finally block to prevent lingering hardware spin states post-execution.

2. Decoupled Flash-Test Pipeline

   • Problem: In high-throughput flashing scenarios, flashing and quality control (PQC) required distinct manual interventions, slowing down deployment.
   • Solution: Added a --test flag to tools/batch_burner.py. When enabled, the runner automatically spawns the updated test_uart.py subprocess 1.0 second after a successful flash (allowing host USB subsystem renegotiation).

3. Documentation Debt

   • Problem: Lack of standardized SOPs for production and environment bootstrapping.
   • Solution: Rewrote README.md to define standard project topology, Espressif asset mirror configs (solving high-latency GitHub downloads in domestic networks), and detailed SOPs for standalone tests and automated pipeline stages.

---

File Changes

• tools/batch_burner.py:
  • Implemented --test argument parser logic.
  • Added sys.executable subprocess invocation targeting the dynamically discovered test_uart.py path.
  • Added pre-flight safety checks validating environment existence of pyserial and test assets.
• tests/test_uart.py:
  • Refactored CLI parser to capture platform-specific tty nodes.
  • Added I/O buffer purge sequence before interface release.
• README.md:
  • Added bootstrap environment variables, flashing pipelines, and QC exit-code expectations.

---

Verification & Test Run

Executed end-to-end regression tests on macOS 15.x target:

1. Dynamic Testing Validation:

   $ python3 tests/test_uart.py /dev/cu.usbmodem11101

   Result: Successfully passed all 26 assertions regarding init handshakes, velocity control, bad-checksum rejection, and out-of-bounds error state machine blocks.

2. Pipeline Integration Validation:

   $ python3 tools/batch_burner.py --test

   Result: Target detected -> Flashed successfully at 921600 bps -> Subprocess executed -> 26 assertions passed on live hardware -> Safe disconnect.