Cultguard Chrome project rules

Build policy
- Never run large Chromium builds locally.
- Use remote builders only for full Chromium/browser builds, rebuilds, or anything expected to compile substantial portions of Chromium.
- Local machine is only for light evaluation, patch inspection, smoke helpers, metadata checks, and other non-heavy tasks.
- If validation requires a real Chromium build, prefer the existing remote workflow first.

Validation guidance
- Local allowed: flake eval, patch apply checks, small helper derivations, detect runner/script changes, targeted non-heavy checks.
- Remote required: `.#browser`, `.#chromium-cultguard`, full detect/build validations that would realize or rebuild Chromium.

Operational preference
- When in doubt, ask before triggering any local build that might leave the evaluation/build-planning stage.