fix(autoresearch): resolve fbuild release firmware

[zackees]

Summary

• resolve AutoResearch firmware from fbuild's current .fbuild/build/release/firmware.bin layout
• retain support for the environment-scoped .fbuild/build/<env>/release/firmware.bin layout
• add regression coverage for both artifact layouts

Validation

• uv run pytest ci/tests/test_fbuild_default_selection.py ci/tests/test_ota_peer_hardening.py ci/tests/test_autoresearch_phases.py -q — 205 passed
• bash lint ci/autoresearch/build_driver.py ci/tests/test_fbuild_default_selection.py — passed
• /clud-review — clean
• fbuild port scan — RP2350W COM18 and ESP32-C6 COM9 healthy
• bash autoresearch rp2350w --net-peer --ota --upload-port COM18 --peer-environment esp32c6 --peer-upload-port COM9 --timeout 120s --skip-lint — cleared the previous missing-firmware failure, accepted the artifact, and reached OTA RPC execution

Remaining HIL result

The peer run now proceeds through beginOtaArtifact, then the ESP32-C6 times out on response ID 3 at the first writeOtaArtifact chunk. That later transport/storage failure is separate from this path-resolution fix.

Relates #3956

Summary by CodeRabbit

• Bug Fixes

  • Improved firmware artifact discovery to support both standard release and environment-specific release layouts.
  • Added fallback handling when the preferred firmware location is unavailable.

• Tests

  • Added coverage for default and environment-specific firmware release paths.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: d6cdaf0c-18cc-4fc4-a75c-4594bc738e56

📥 Commits

Reviewing files that changed from the base of the PR and between ed7e0be and 8530300.

📒 Files selected for processing (2)

• ci/autoresearch/build_driver.py
• ci/tests/test_fbuild_default_selection.py

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📝 Walkthrough

Walkthrough

FbuildDriver.firmware_path now selects firmware from default or environment-specific release directories. Tests cover both layouts.

Changes

Firmware path resolution

Layer / File(s)	Summary
Release artifact selection and validation ci/autoresearch/build_driver.py, ci/tests/test_fbuild_default_selection.py	The driver checks the default release artifact, then the environment-specific release artifact, and falls back to the default release path. Tests cover both release layouts.

Estimated code review effort: 2 (Simple) | ~10 minutes

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/autoresearch-fbuild-firmware-path

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