chore: remove ota_POC.py proof-of-concept (unsafe DFU activation)

[balloob]

Summary

Removes ota_POC.py from the repo root. It is a proof-of-concept that is unsafe to run and duplicates functionality already provided correctly by the maintained library src/nrf_ota/dfu.py.

The hazard

In ota_POC.py, the firmware VALIDATE step treats status INVALID_STATE (0x02) as success:

status = rsp[2]
if status not in (0x01, 0x02):
    raise RuntimeError(f"Validation failed with status {status}")

It then unconditionally calls activate_and_reset(). For this Legacy bootloader, dfu_image_validate() returns INVALID_STATE exactly when the received byte count does not match the image size (a data packet was dropped in transit) — it is not an alternate success. Firing Activate at that point resets the device without writing the valid-app settings and leaves it stuck in DFU. Legacy DFU cannot retransmit, so this is a real bricking-into-DFU footgun.

The maintained library already documents and handles this exact case correctly in src/nrf_ota/dfu.py (it raises a clear, retryable DFUError on INVALID_STATE instead of activating).

Why it's safe to remove

• ota_POC.py was already excluded from the built wheel (only src/nrf_ota is packaged).
• Nothing in the repo imports it — it was a standalone script sitting next to the correct library, a footgun for anyone who ran it directly.
• The now-dead references to it in pyproject.toml (ruff exclude) and .github/CODEOWNERS are removed as well.

No changes to the library itself. uv run pytest -q passes (30 passed).

🤖 Generated with Claude Code

https://claude.ai/code/session_012g2e8mr132vcizx92WsgiR

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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