feat(ui): TASK 42 top bar redesign — one Record-or-Stream surface (2026-09-22)

The bar now renders ONE surface from the FIRST decision the creator makes —
Record or Stream — with each world being the whole bar. Creator directive:
"I wrote the fucking thing and I still can't figure-out how to do stuff",
"forget this one dog plan bullshit". OBS/streaming-tool reference for the
one-surface paradigm: https://obsproject.com (single mode toggle + context
actions) — cited per spin-guard habit; the go-live/test pattern follows
CEV (https://cev-desktop.aSean.xyz) precedent.

- Mode: single segmented REC|ON-AIR switch (SegmentToggle/SegmentLabel in
  Themes/Controls.xaml); radio-exclusive world selection, one tap to flip.
- Record world: switch + Start Recording, zero YouTube identity.
- Stream world: switch + Go Live + Test + account zone right (Sign In until
  connected, then avatar with Change Account/Logout context menu).
- Test is a child of Stream: procs only stream-armed AND signed-in.
- Running: one reality line "dot word elapsed" (REC/LIVE/TEST; green/red/
  gold) + End; worlds + switch retire.
- Gear moved up from bottom bar, ~3 wordmark letters past the brand, single
  click opens Settings/Bug/Feature/About menu (TASK 40 Unit B shipped early).
- Fix folded in: BeginTestStream now arms OnAirPillOn explicitly (unarmed
  pump booted with zero encoder outputs -> "At least one output is required"
  forced-stop cascade from TASK 41's pipeline).
- VM: world/reality props + RaiseTopBarModes() wired into StreamStatus,
  pill, IsRecording, IsTestStream, IsConnected setters.

Doc: ai.md top-bar model, ViewModels/index.md, Controls/index.md, TASKS.md,
HANDOFF.md, new TASKS/task-42-top-bar-redesign.md; task-40 note.

Tests: TopBarModeTests.cs (new Good Dog), PillRadioTests + TestStreamTests
gates updated. Build 0 warnings; full suite 314/315 — single abort is the
pre-existing env-dependent RealMouseDrag test (Path of Exile 2 running)

ViewModels/MainViewModel.Streaming.Operations.cs

@@ -94,6 +94,11 @@ public partial class MainViewModel : ViewModelBase
     private void BeginTestStream()
     {
         if (!CanStartTest) return;
+        // Test is stream-world-only, so the ON-AIR intent is armed by the time we
+        // get here — but arm it explicitly anyway: the encoder output gate reads the
+        // pill (StreamEnabled = OnAirPillOn), and a test that never armed the pill
+        // boots a pump with zero outputs and dies on "At least one output required".
+        OnAirPillOn = true;
         IsTestStream = true; // before StreamStatus so the visuals initialize gold
         StreamTitle = BroadcastForm.Title;
         StreamDescription = BroadcastForm.Description;