[FARMSLOT DEMO - DO NOT MERGE] Command Center: red debug banner for dispatch smoke test

[deeeed]

Summary

Add a demo-only red debug banner to Command Center so operators can prove Farmslot dispatch → worktree → UI validation end-to-end. This issue is a smoke task for the unified farmslot project on macwork-ff-* sandboxes — not product UI to ship.

DO NOT MERGE — branch/PR must stay clearly marked demo-only.

Change

When demo mode is enabled, show a fixed red banner on Command Center with exact text:

FARMSLOT DEMO: PARALLEL RUN MONITORING

Scope

• Touch Command Center UI only (apps/command-center/ui/).
• Gate behind an explicit demo flag/env (e.g. VITE_FARMSLOT_DEMO_BANNER=1 or existing demo profile) so normal usage is unchanged.
• Banner: high-contrast red bar, readable on dark theme, does not block primary navigation.

Out of scope

• Gateway/protocol changes
• Companion/mobile
• Merging to main

Acceptance criteria

1. With demo flag off, banner is not visible anywhere in Command Center.
2. With demo flag on, banner shows on the main shell (slot view or app chrome) with text exactly: FARMSLOT DEMO: PARALLEL RUN MONITORING.
3. Change is isolated (one component + minimal wiring), easy to revert.
4. yarn typecheck in apps/command-center passes.
5. Recipe proof required — author TASK_DIR/artifacts/recipe.json (start from docs/examples/recipes/farmslot/demo-red-banner.recipe.json), run via projects/farmslot/setup/validate-recipe.sh, and write recipe-coverage.md + recipe-quality.json. No direct UI state injection.

Validation hints for agent

# worktree sandbox (macwork-ff-2 example)
cd apps/command-center && yarn typecheck
bash apps/command-center/scripts/debug-chrome.sh
node apps/command-center/scripts/agentic/recipe-doctor.mjs --cdp-port <cdp> --gateway-port 8809 --slot-id macwork-ff-2 --json

# After implementation — recipe must exit 0
bash projects/farmslot/setup/validate-recipe.sh \
  --recipe .sandbox/farmslot/worker-task/feat/<task>/artifacts/recipe.json \
  --artifacts-dir .sandbox/farmslot/worker-task/feat/<task>/artifacts/recipe-run \
  --platform cli --cdp-port <cdp> --gateway-port 8809 --slot-id macwork-ff-2

Operator notes

• Project: farmslot, slot: macwork-ff-2, prepare: sandbox
• Work happens in farmslot-wt/farmslot-2 worktree, not main clone
• Worker templates now require Recipe v1 proof for Command Center UI tasks