docs: add Copilot instructions for repository guidelines

Co-authored-by: abhi1693 <5083532+abhi1693@users.noreply.github.com>

.github/copilot-instructions.md

@@ -0,0 +1,39 @@
+# Repository Guidelines
+
+## Project Structure & Module Organization
+- `backend/`: FastAPI service. Main app code lives in `backend/app/` with API routes in `backend/app/api/`, data models in `backend/app/models/`, schemas in `backend/app/schemas/`, and service logic in `backend/app/services/`.
+- `backend/migrations/`: Alembic migrations (`backend/migrations/versions/` for generated revisions).
+- `backend/tests/`: pytest suite (`test_*.py` naming).
+- `backend/templates/`: backend-shipped templates used by gateway flows.
+- `frontend/`: Next.js app. Routes under `frontend/src/app/`, shared components under `frontend/src/components/`, utilities under `frontend/src/lib/`.
+- `frontend/src/api/generated/`: generated API client; regenerate instead of editing by hand.
+- `docs/`: contributor and operations docs (start at `docs/README.md`).
+
+## Build, Test, and Development Commands
+- `make setup`: install/sync backend and frontend dependencies.
+- `make check`: closest CI parity run (lint, typecheck, tests/coverage, frontend build).
+- `docker compose -f compose.yml --env-file .env up -d --build`: run full stack.
+- Fast local loop:
+  - `docker compose -f compose.yml --env-file .env up -d db`
+  - `cd backend && uv run uvicorn app.main:app --reload --port 8000`
+  - `cd frontend && npm run dev`
+- `make api-gen`: regenerate frontend API client (backend must be on `127.0.0.1:8000`).
+
+## Coding Style & Naming Conventions
+- Python: Black + isort + flake8 + strict mypy. Max line length is 100. Use `snake_case`.
+- TypeScript/React: ESLint + Prettier. Components use `PascalCase`; variables/functions use `camelCase`.
+- For intentionally unused destructured TS variables, prefix with `_` to satisfy lint config.
+
+## Testing Guidelines
+- Backend: pytest via `make backend-test`; coverage policy via `make backend-coverage` (writes `backend/coverage.xml` and `backend/coverage.json`).
+- Frontend: vitest + Testing Library via `make frontend-test` (coverage in `frontend/coverage/`).
+- Add or update tests whenever behavior changes.
+
+## Commit & Pull Request Guidelines
+- Follow Conventional Commits (seen in history), e.g. `feat: ...`, `fix: ...`, `docs: ...`, `test(core): ...`.
+- Keep PRs focused and based on latest `master`.
+- Include: what changed, why, test evidence (`make check` or targeted commands), linked issue, and screenshots/logs when UI or operator workflow changes.
+
+## Security & Configuration Tips
+- Never commit secrets. Copy from `.env.example` and keep real values in local `.env`.
+- Report vulnerabilities privately via GitHub security advisories, not public issues.