refactor(web): reorganize phases + fix Open-your-node URL

Move sections to where they read better:
- Phase 1 (Team registration): drop the "Your Agent" block.
- Phase 2 (Meet your agent): host the "Your Agent" section (say-hi / Telegram /
  voice) AND the agent chat under it; remove "Pick your domain".
- Module 1 (Domain & events): "Pick your domain" moves here (no more read-only
  carry) alongside the ADD Layer 1 card.
- Module 2 (Skills & policies): the chat is gone; the L2/L3 ADD cards show
  directly (still auto-prefilled if the three prompts ran in Meet your agent).

Also: OpenYourNode opens the browser-reachable board URL. In self-host/USB mode
the stored url is container-facing (host.docker.internal) which the browser
can't resolve — derive the current host on :8080 instead. Tests updated.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/components/BuildFlash.test.tsx

@@ -18,6 +18,8 @@ vi.mock('@/lib/api', () => ({
     liveOnEvent = onEvent
     return closeSpy
   },
+  // OpenYourNode (rendered here) reads the runtime mode.
+  getMode: () => Promise.resolve({ localMode: false }),
 }))
 
 describe('BuildFlash', () => {