Document Codex contribution trail

Record the Codex-assisted planning, scaffold, stack, and schema work so the repository has an explicit contribution trail for the hackathon submission.

Co-authored-by: OpenAI Codex <codex@openai.com>

docs/CODEX_USAGE_LOG.md

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+# Codex Usage Log
+
+This project is being developed with OpenAI Codex assistance.
+
+The hackathon plan targets Best Use of Codex, so this log records where Codex contributed beyond one-off prompting.
+
+## 2026-06-09
+
+### Planning and repo setup
+
+- Created the local BugLens project repository.
+- Added the five-file planning pack under `docs/plans`.
+- Initialized Git and pushed the repository to GitHub.
+- Added a lightweight app scaffold with `app.py`, `modal_app.py`, `buglens/`, `tests/`, and dependency files.
+
+Related commits:
+
+- `232f5e1 Initialize BugLens planning scaffold`
+
+### Verified stack foundation
+
+- Started from `docs/plans/01_research_verified_stack.md`.
+- Added `uv` as the official package workflow.
+- Added `pyproject.toml`, `uv.lock`, `.env.example`, and `UV.md`.
+- Added runtime config for the selected model and backend modes.
+- Implemented the first Pydantic contract for structured BugLens reports.
+- Added passing schema tests through `uv run pytest tests/test_schema.py`.
+
+Related commits:
+
+- `ee326f7 Add verified stack foundation`
+
+## Attribution Note
+
+The first two commits were made through the local terminal using the configured Git identity:
+
+```text
+vatche.thorossian <vatche.thorossian@digitain.com>
+```
+
+Future Codex-assisted commits should include an explicit trailer:
+
+```text
+Co-authored-by: OpenAI Codex <codex@openai.com>
+```
+
+For the strongest possible hackathon proof, also use the official OpenAI Codex GitHub integration for later implementation commits if available.
+