[FARMSLOT DEMO - DO NOT MERGE] Companion: red debug banner for mobile dispatch smoke

[abretonc7s]

Summary

Demo-only red banner on Mobile Companion to exercise farmslot dispatch → worktree → iOS recipe proof → publication gate. DO NOT MERGE.

Acceptance criteria

1. With demo flag off, banner is not visible anywhere in Companion.
2. With demo flag on, banner shows on the main shell with text exactly: FARMSLOT DEMO: MOBILE OPERATOR MONITORING
3. Change is isolated (one component + env wiring), easy to revert.
4. cd apps/companion && yarn typecheck passes.
5. Recipe proof on iOS simulator via companion runner (platform: ios), not typecheck alone.
6. (Recommended) Companion run-detail can open Run A and show its recipe evidence (before/after from [FARMSLOT DEMO - DO NOT MERGE] Command Center: red debug banner for dispatch smoke test #28).