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).

gateway/internal/connectsrv/server_test.go

@@ -53,6 +53,33 @@ func newEdgeMin(t *testing.T, minVersion string, backendHandler http.HandlerFunc
 	}
 }
 
+// newEdgeVersions is newEdgeMin with the soft-tier recommended version also armed (empty leaves it off).
+func newEdgeVersions(t *testing.T, minVersion, recommendedVersion string, backendHandler http.HandlerFunc) (edgev1connect.GatewayClient, func()) {
+	t.Helper()
+	backendSrv := httptest.NewServer(backendHandler)
+	backend, err := backendclient.New(backendSrv.URL, "localhost:9090", 2*time.Second)
+	if err != nil {
+		t.Fatalf("backendclient: %v", err)
+	}
+	edge := connectsrv.NewServer(connectsrv.Deps{
+		Registry:                 transcode.NewRegistry(backend, nil),
+		Sessions:                 session.NewCache(backend, time.Minute, 100),
+		Limiter:                  ratelimit.New(),
+		Hub:                      push.NewHub(0),
+		RateLimit:                config.DefaultRateLimit(),
+		Heartbeat:                15 * time.Second,
+		MinClientVersion:         minVersion,
+		RecommendedClientVersion: recommendedVersion,
+	})
+	edgeSrv := httptest.NewServer(edge.HTTPHandler())
+	client := edgev1connect.NewGatewayClient(http.DefaultClient, edgeSrv.URL)
+	return client, func() {
+		edgeSrv.Close()
+		_ = backend.Close()
+		backendSrv.Close()
+	}
+}
+
 func TestExecuteGuestAuthOK(t *testing.T) {
 	client, cleanup := newEdge(t, func(w http.ResponseWriter, r *http.Request) {
 		_, _ = w.Write([]byte(`{"token":"tok","user_id":"u-1","is_guest":true,"display_name":"Guest"}`))
@@ -156,6 +183,54 @@ func TestExecuteVersionGate(t *testing.T) {
 	}
 }
 
+// TestExecuteUpdateRecommended verifies the soft-tier nudge on the unary path: a served client at or
+// above the hard minimum but below the recommended version gets the X-Update-Recommended response
+// header (the call still succeeds); a too-old (hard-gated), up-to-date, absent, or unparseable version
+// and a dormant soft tier get no header.
+func TestExecuteUpdateRecommended(t *testing.T) {
+	backend := func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte(`{"token":"tok","user_id":"u-1","is_guest":true,"display_name":"Guest"}`))
+	}
+	tests := []struct {
+		name       string
+		min        string
+		rec        string
+		header     string
+		wantResult string
+		wantHeader bool
+	}{
+		{"soft band is nudged", "v1.16.0", "v1.20.0", "v1.17.0", "ok", true},
+		{"at the minimum is nudged", "v1.16.0", "v1.20.0", "v1.16.0", "ok", true},
+		{"at the recommended is not nudged", "v1.16.0", "v1.20.0", "v1.20.0", "ok", false},
+		{"newer than recommended is not nudged", "v1.16.0", "v1.20.0", "v2.0.0", "ok", false},
+		{"too old is gated, not nudged", "v1.16.0", "v1.20.0", "v1.0.0", "update_required", false},
+		{"absent header, no nudge", "v1.16.0", "v1.20.0", "", "ok", false},
+		{"unparseable header, no nudge", "v1.16.0", "v1.20.0", "dev", "ok", false},
+		{"recommended alone (no min) nudges below it", "", "v1.20.0", "v1.0.0", "ok", true},
+		{"soft tier dormant, no nudge", "v1.16.0", "", "v1.0.0", "update_required", false},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			client, cleanup := newEdgeVersions(t, tc.min, tc.rec, backend)
+			defer cleanup()
+			req := connect.NewRequest(&edgev1.ExecuteRequest{MessageType: transcode.MsgAuthGuest, RequestId: "rq"})
+			if tc.header != "" {
+				req.Header().Set("X-Client-Version", tc.header)
+			}
+			resp, err := client.Execute(context.Background(), req)
+			if err != nil {
+				t.Fatalf("execute: %v", err)
+			}
+			if got := resp.Msg.GetResultCode(); got != tc.wantResult {
+				t.Fatalf("result_code = %q, want %q", got, tc.wantResult)
+			}
+			if got := resp.Header().Get("X-Update-Recommended") == "1"; got != tc.wantHeader {
+				t.Fatalf("X-Update-Recommended present = %v, want %v", got, tc.wantHeader)
+			}
+		})
+	}
+}
+
 // TestSubscribeVersionGate verifies the streaming path: a too-old client is refused with
 // FailedPrecondition, while an equal or absent version is admitted and proceeds to auth (which
 // fails Unauthenticated with no session, proving it passed the version gate).