feat(offline): implicit net-state model, two-tier version gate, unified lobby

Land the offline-model redesign (ANDROID_PLAN.md O1-O7): replace the explicit offline toggle with a single detected net-state machine, unify the lobby, and add a two-tier client-version gate. Contour-safe: both version vars empty => dormant, and the wire change is additive, so web/pwa/vk/tg behaviour is unchanged unless the gate is deliberately configured.

O1 pure net-state reducer (test-first). O2 reactive store + event wiring (connection/offline become thin shims; +@capacitor/network). O3 remove the offline toggle + migrate the pref. O4 two-tier gate: hard update_required degrades to an offline Update/Play-offline notice (not terminal); soft GATEWAY_RECOMMENDED_CLIENT_VERSION -> X-Update-Recommended nudge. O5 unified lobby (device-local + greyed-from-cache server games; self-set identity; closes G-step-0). O6 create flows (with-friends online/offline segment + offline dict guard). O7 docs (ARCHITECTURE, FUNCTIONAL +_ru, TESTING, deploy/README).

Also disable the manual android-build CI workflow for now (rename to .disabled); the Android APK release comes later.

Tests: gateway go green, svelte-check 0/0, vitest 617, e2e 122/122 (chromium + webkit).

ui/src/components/UpdateOverlay.svelte

@@ -1,33 +1,29 @@
 <script lang="ts">
-  // Non-dismissable "update required" cover. Shown when the gateway has refused a foreground call
-  // as too old (update.svelte.ts — the client-version gate). Unlike the maintenance overlay this is
-  // terminal: an installed build cannot become compatible without an actual update, so its one
-  // action takes the user to the fix — the store listing on a native build (VITE_RUSTORE_URL, opened
-  // in the system browser / store app) or a plain reload on the web (which fetches the current
-  // client). Mirrors MaintenanceOverlay.svelte's look.
-  import { updateRequired } from '../lib/update.svelte';
-  import { clientChannel } from '../lib/channel';
+  // The "update required" notice (the hard version tier). Shown when the gateway has refused a
+  // foreground call as too old, driving the net-state machine into offlineVersionLocked. Unlike the
+  // old terminal cover it is dismissable: "Update" takes the user to the fix (the store on native,
+  // a reload on the web), while "Play offline" dismisses the notice and leaves the app in the offline
+  // lobby (the version lock is an offline state, sticky until an actual update on the next launch).
+  // Mirrors MaintenanceOverlay.svelte's look.
+  import { netState } from '../lib/netstate.svelte';
+  import { openUpdate } from '../lib/update.svelte';
   import { t } from '../lib/i18n/index.svelte';
 
-  function onAction(): void {
-    const ch = clientChannel();
-    if (ch === 'android' || ch === 'ios') {
-      // '_system' hands the URL to the OS (the store app / external browser) rather than the WebView.
-      const url = import.meta.env.VITE_RUSTORE_URL;
-      if (url) window.open(url, '_system');
-    } else {
-      location.reload();
-    }
-  }
+  // Dismissed for the session once the user chooses "Play offline". The lock is sticky until a fresh
+  // launch, so the notice does not reappear this session; the app stays in the offline lobby.
+  let dismissed = $state(false);
 </script>
 
-{#if updateRequired.active}
+{#if netState.versionLocked && !dismissed}
   <div class="scrim" role="alertdialog" aria-modal="true" aria-labelledby="update-title" aria-describedby="update-body">
     <div class="card">
       <div class="tile" aria-hidden="true">Э</div>
       <h1 id="update-title">{t('update.title')}</h1>
       <p id="update-body">{t('update.body')}</p>
-      <button type="button" onclick={onAction}>{t('update.action')}</button>
+      <div class="acts">
+        <button type="button" class="primary" onclick={openUpdate}>{t('update.action')}</button>
+        <button type="button" onclick={() => (dismissed = true)}>{t('update.playOffline')}</button>
+      </div>
     </div>
   </div>
 {/if}
@@ -36,8 +32,7 @@
   .scrim {
     position: fixed;
     inset: 0;
-    /* Above the game (z 60) and toasts (z 50) — a terminal update block covers everything the user
-       could otherwise interact with; below the dev DebugPanel (z 10000). */
+    /* Above the game (z 60) and toasts (z 50); below the dev DebugPanel (z 10000). */
     z-index: 100;
     background: rgba(0, 0, 0, 0.55);
     display: grid;
@@ -79,6 +74,11 @@
     color: var(--text-muted);
     line-height: 1.5;
   }
+  .acts {
+    display: flex;
+    flex-direction: column;
+    gap: 0.6rem;
+  }
   button {
     font: inherit;
     padding: 0.55rem 1.4rem;
@@ -92,4 +92,13 @@
     border-color: var(--accent);
     color: var(--accent);
   }
+  .primary {
+    background: var(--accent);
+    color: var(--accent-text);
+    border-color: var(--accent);
+  }
+  .primary:hover {
+    color: var(--accent-text);
+    opacity: 0.9;
+  }
 </style>