Demo mode: time-to-wow under 60 seconds without OAuth

[khaliqgant]

The current setup path (install → OAuth → sync wait → wait for a real event) has four dropout points before anyone sees the product work. We need to decouple the first wow moment from OAuth entirely.

Proposed: relayfile dev demo mode

When no credentials are found, relayfile dev connects to a hosted demo workspace instead of exiting with a setup prompt. Synthetic events fire within ~5 seconds so the user's --run command executes immediately against real-looking data.

npx relayfile dev \
  --path "/linear/issues/by-state/triage/**" \
  --event file.created \
  --run "echo 'Triaging: {{path}}'"

After the first event fires, print a one-line upgrade prompt:

[demo] Got it working? Connect the real thing: relayfile setup --provider linear

What needs to exist

1. Demo fallback in relayfile dev — detect no credentials, connect to demo workspace, show [demo] banner
2. Hosted demo workspace — synthetic events cycling on ~10s loop, realistic paths and payloads (Linear triage issue, GitHub PR, HubSpot deal)
3. Post-event upgrade prompt — carries current flags into the suggested setup command
4. npx packaging — no binary install step before the demo

Why this order

The user writes their --run command before doing OAuth. Setup becomes connecting real data to something they've already confirmed works — not a leap of faith into a blank terminal.