0.2.2 + 0.3.0: remote threading fix, phone-first onboarding, ten-foot settings, self-healing errors, in-app updater, group filter

Squashed history rewrite: earlier revisions of the docs carried private
hostnames; placeholders throughout history now.

- Fix phone remote threading (welcome/get_state/broadcast) — remote connects
  and mirrors channels, Now/Next, favorites
- Phone-first onboarding (ADR-0007): one QR, server URL + IdP login on the
  phone (closes #11)
- Ten-foot settings + Erweitert sub-screen (closes #14), TvTextField D-pad
  focus fix (closes #9)
- EPG grid envelope parsing, Now/Next live (closes #10)
- Self-healing error states (closes #13), in-app updater (closes #12)
- Channel group filter chips fed by Dispatcharr groups

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CONTEXT.md

@@ -18,8 +18,15 @@ _Avoid_: pairing (that word is reserved for the Remote)
 
 **Backend (Dispatcharr)**:
 The self-hosted stream manager owning sources, aggregation, failover, EPG and
-stream profiles; forked at be-nj with native OIDC.
-_Avoid_: server (ambiguous), nodecast (dropped, see ADR-0003)
+stream profiles; forked at be-nj with native OIDC. Admin UI internal
+(<admin-host>), API external for TV clients (api.<viewer-host>).
+_Avoid_: server (ambiguous)
+
+**Viewer (nodecast)**:
+The browser frontend for the family on <viewer-host> — OIDC login, plays
+via its own transcode; consumes exactly one source, the Backend's M3U/EPG
+output (ADR-0006).
+_Avoid_: treating it as a second source of truth
 
 **Quelle (Source)**:
 A configured backend the TV-App reads channels from — primary type Dispatcharr
@@ -38,6 +45,16 @@ Trusting a Remote via the QR token (128-bit) or the rate-limited 4-digit code.
 A playable live entry the Backend exposes via Xtream API or M3U.
 _Avoid_: station, sender (in code/docs)
 
+**Onboarding**:
+First-run flow: the TV shows one QR (its own pairing server); server URL and
+the IdP login then happen entirely on the phone via the Remote. Nothing is
+ever typed on the TV.
+
+**Ten-Foot-Regel**:
+In the family path the TV UI has no text fields and no scrolling except the
+channel list itself; every screen fits the screen. Text-heavy configuration
+lives in an "Erweitert" sub-screen.
+
 **Now/Next**:
 The EPG scope of the Remote in phase 1: current + upcoming programme per
 Channel, no full guide timeline.