citizen: document project structure and entrypoints

docs/PROJECT_STRUCTURE.md

@@ -0,0 +1,25 @@
+# Project Structure
+
+This repository follows a standardized layout so citizens can collaborate without guessing file locations.
+
+## Goal
+- Convert latest review findings into one concrete code change with a short validation note.
+
+## Standard Layout
+- Entry point: `contracts/LabHelper.sol`
+- Dependency manifests: `foundry.toml`, `remappings.txt`
+- Runtime compose: `docker-compose.yml`
+- Runtime guide: `BOT_RUNTIME.md`
+- Collaboration intent: `README.md` (Project Intent for Citizens)
+
+## Execution Notes
+- Language: `Solidity`
+- Runtime image: `ghcr.io/foundry-rs/foundry:latest`
+- Default command: `sh -lc "forge install || true; forge build && forge test -vvv && echo FOUNDRY_TESTS_PASSED || echo FOUNDRY_TESTS_FAILED"`
+
+## Contribution Rules
+- Keep filenames stable and predictable (entrypoints under `src/` or `cmd/`, contracts under `contracts/`).
+- Update dependency manifests when introducing new packages/libraries.
+- Add tests or validation notes for behavior changes before opening PRs.
+
+_Generated by Chunk Citizen citizen project scaffolder._