docs(repo): add Cursor Cloud specific instructions to AGENTS.md

[Gsbreddy]

Summary

Add ## Cursor Cloud specific instructions section to AGENTS.md with a quick-reference table and gotchas for future Cloud Agents working in this repo.

Why

Future Cursor Cloud agent sessions need non-obvious startup/run caveats documented so they can immediately run lint, tests, and the application without re-discovering setup details each time.

Changes

• Added ## Cursor Cloud specific instructions section to AGENTS.md with:
  • Quick reference table (deps install, lint, test, smoke, schema check, CLI, HTTP server)
  • Gotchas (Python 3.14 strict requirement, flightdeck init prerequisite, --frozen flag, temp dir configuration, schema drift)

Validation

• python -m ruff check src tests — All checks passed
• python -m pytest — 48 tests passed
• CLI smoke test (uv run python scripts/quickstart_smoke.py) — OK
• Schema generation + no drift check — OK
• Full quickstart demo (init, pricing, policy, register, ingest, diff, promote, history)
• HTTP server (flightdeck serve) + event ingestion via POST /v1/events

Schema / Storage Impact

• None

Risk

None — documentation-only change.

Notes

The update script for the VM environment installs uv, Python 3.14, and syncs dev dependencies.