fix(offline): set the auto flag in setOfflineMode; remove temp diagnostic

The auto-offline -> online return was dead because setOfflineMode never set the
'auto' flag: I added the state + getter but forgot the assignment, so it stayed
false. So scheduleRecovery bailed immediately (no poll ran) and the online event's
'if (active && auto)' was false. The contour diagnostic confirmed offline.auto
stayed false after an auto-offline. Add 'auto = on && !persist'.

Also remove the temporary network diagnostic panel (netdiag + the lobby strip) --
it did its job of pinpointing this.

ui/src/lib/app.svelte.ts

@@ -57,7 +57,6 @@ import {
 import type { CoachSeries } from './coachmark';
 import { connection, reportOffline, reportOnline, resetConnection, checkReachable } from './connection.svelte';
 import { offlineMode, setOfflineMode } from './offline.svelte';
-import { netlog } from './netdiag.svelte'; // TEMP diagnostic
 import { shouldBootOffline } from './offline';
 import { isConnectionCode } from './retry';
 import { clearGameCache, getCachedGame, setCachedGame } from './gamecache';
@@ -604,15 +603,9 @@ export function scheduleRecovery(delayMs: number): void {
     recoveryTimer = null;
     if (!offlineMode.active || !offlineMode.auto) return;
     const interfaceUp = typeof navigator === 'undefined' || navigator.onLine;
-    netlog(`poll tick: navOnline=${interfaceUp}`); // TEMP diagnostic
-    if (interfaceUp) {
-      const reachable = await checkReachable(BOOT_REACHABILITY_TIMEOUT_MS);
-      netlog(`checkReachable=${reachable}`); // TEMP diagnostic
-      if (reachable && offlineMode.active && offlineMode.auto) {
-        setOfflineMode(false);
-        netlog('-> RETURNED ONLINE'); // TEMP diagnostic
-        return;
-      }
+    if (interfaceUp && (await checkReachable(BOOT_REACHABILITY_TIMEOUT_MS))) {
+      if (offlineMode.active && offlineMode.auto) setOfflineMode(false);
+      return;
     }
     scheduleRecovery(4000);
   }, delayMs);
@@ -621,17 +614,14 @@ export function scheduleRecovery(delayMs: number): void {
 export function initNetworkReactivity(): void {
   if (typeof window === 'undefined' || import.meta.env.MODE === 'mock') return;
   window.addEventListener('offline', () => {
-    netlog(`offline EVENT (active=${offlineMode.active})`); // TEMP diagnostic
     if (!offlineMode.active) {
       setOfflineMode(true, false); // auto (session)
-      netlog('-> auto-offline; poll started'); // TEMP diagnostic
       scheduleRecovery(4000); // poll for the network to return
     }
   });
   // The online event, when it fires, just kicks an immediate reachability check; the poll above is
   // the reliable fallback for platforms where it does not fire.
   window.addEventListener('online', () => {
-    netlog(`online EVENT (active=${offlineMode.active} auto=${offlineMode.auto})`); // TEMP diagnostic
     if (offlineMode.active && offlineMode.auto) scheduleRecovery(0);
   });
 }

ui/src/lib/netdiag.svelte.ts

@@ -1,38 +0,0 @@
-// TEMPORARY network diagnostic — REMOVE before release. A live view of the online/offline signals so
-// we can pinpoint where the auto-offline -> online transition breaks. Rendered by a panel in
-// Lobby.svelte. Skipped in the mock build.
-
-let entries = $state<string[]>([]);
-let navOnline = $state(typeof navigator !== 'undefined' ? navigator.onLine : true);
-
-export const netdiag = {
-  /** entries is the newest-first ring buffer of timestamped diagnostic lines. */
-  get entries(): string[] {
-    return entries;
-  },
-  /** navOnline is the live navigator.onLine value (the property itself is not reactive). */
-  get navOnline(): boolean {
-    return navOnline;
-  },
-};
-
-/** netlog appends a timestamped diagnostic line (kept to the last 24). */
-export function netlog(msg: string): void {
-  const t = new Date().toLocaleTimeString();
-  entries = [`${t}  ${msg}`, ...entries].slice(0, 24);
-  if (typeof navigator !== 'undefined') navOnline = navigator.onLine;
-}
-
-// A 1 s heartbeat keeps navigator.onLine live in the panel and logs when it flips — so a flight-mode
-// toggle is visible even if the online/offline events never fire (the exact thing we are chasing).
-if (typeof window !== 'undefined' && import.meta.env.MODE !== 'mock') {
-  let last = typeof navigator !== 'undefined' ? navigator.onLine : true;
-  setInterval(() => {
-    const now = typeof navigator !== 'undefined' ? navigator.onLine : true;
-    navOnline = now;
-    if (now !== last) {
-      last = now;
-      netlog(`navigator.onLine -> ${now}`);
-    }
-  }, 1000);
-}

ui/src/lib/offline.svelte.ts

@@ -36,6 +36,7 @@ export const offlineMode = {
  */
 export function setOfflineMode(on: boolean, persist = true): void {
   active = on;
+  auto = on && !persist; // a non-persisted offline is auto-detected; a persisted one is deliberate
   if (persist) saveOfflinePref(on);
 }
 

ui/src/screens/Lobby.svelte

@@ -6,7 +6,6 @@
   import Modal from '../components/Modal.svelte';
   import { app, handleError, refreshFeedbackBadge, seedChatUnread } from '../lib/app.svelte';
   import { connection } from '../lib/connection.svelte';
-  import { netdiag } from '../lib/netdiag.svelte'; // TEMP diagnostic
   import { gateway } from '../lib/gateway';
   import { navigate } from '../lib/router.svelte';
   import { t } from '../lib/i18n/index.svelte';
@@ -259,15 +258,6 @@
   }
 </script>
 
-<!-- TEMP network diagnostic — REMOVE before release. Fixed strip showing the live online/offline
-     signals + an event log, to pinpoint where the auto-offline -> online transition breaks. -->
-<div style="position:fixed;top:0;left:0;right:0;z-index:9999;background:rgba(0,0,0,0.88);color:#0f0;font:10px/1.35 monospace;padding:4px 6px;max-height:45vh;overflow-y:auto;pointer-events:none">
-  <div style="color:#fff;margin-bottom:3px">
-    nav.onLine={String(netdiag.navOnline)} · offline={String(offlineMode.active)} · auto={String(offlineMode.auto)} · conn.online={String(connection.online)}
-  </div>
-  {#each netdiag.entries as e, i (i)}<div style="white-space:nowrap">{e}</div>{/each}
-</div>
-
 <Screen title={app.profile?.displayName ?? t('app.title')}>
   <div class="lobby">
     {#if invitations.length}