fix(ui): copy GCG to clipboard on Android in-app WebViews

On-device diagnostics from Android Telegram and VK confirmed both expose
no navigator.share AND no navigator.canShare, so the export fell to a Blob
<a download> that those WebViews silently ignore — nothing happened.

pickGcgDelivery is now a 3-way decision: Web Share where available (iOS),
a clipboard copy in an Android in-app WebView (Telegram/VK: no share, dead
download), else a desktop Blob download. shareOrDownloadGcg reports the
outcome so the game shows a "GCG copied" toast; the copy is VKWebAppCopyText
inside VK (which also covers the desktop VK iframe, where navigator.clipboard
is blocked) and navigator.clipboard otherwise.

Unit tests cover the 3-way choice and the copy/failed outcomes; new i18n key
game.gcgCopied (en+ru); docs ARCHITECTURE/FUNCTIONAL(+ru)/UI_DESIGN/TESTING.

ui/src/lib/share.test.ts

@@ -7,26 +7,31 @@ const file = {} as File;
 const gcg: GcgExport = { gameId: 'g1', filename: 'game.gcg', content: '#title game' };
 
 describe('pickGcgDelivery', () => {
-  it('shares when the platform can share files', () => {
-    expect(pickGcgDelivery({ canShare: () => true, share: async () => {} }, file)).toBe('share');
+  const canShareNav = { canShare: () => true, share: async () => {} };
+  const noShareNav = { canShare: () => false, share: async () => {} };
+
+  it('shares when the platform can share files, even in an in-app webview (iOS)', () => {
+    expect(pickGcgDelivery(canShareNav, file, false)).toBe('share');
+    expect(pickGcgDelivery(canShareNav, file, true)).toBe('share');
   });
 
-  it('downloads when the platform cannot share files', () => {
-    expect(pickGcgDelivery({ canShare: () => false, share: async () => {} }, file)).toBe('download');
+  it('copies in an in-app webview that cannot share files (Android Telegram/VK: no share, dead download)', () => {
+    expect(pickGcgDelivery(noShareNav, file, true)).toBe('copy');
+    expect(pickGcgDelivery(undefined, file, true)).toBe('copy');
+    expect(pickGcgDelivery({ canShare: () => true } as never, file, true)).toBe('copy');
   });
 
-  it('downloads when there is no navigator', () => {
-    expect(pickGcgDelivery(undefined, file)).toBe('download');
-  });
-
-  it('downloads when the Web Share API is incomplete', () => {
-    expect(pickGcgDelivery({ canShare: () => true } as never, file)).toBe('download');
+  it('downloads on a plain browser without Web Share (desktop)', () => {
+    expect(pickGcgDelivery(noShareNav, file, false)).toBe('download');
+    expect(pickGcgDelivery(undefined, file, false)).toBe('download');
   });
 });
 
 describe('shareOrDownloadGcg', () => {
   afterEach(() => vi.unstubAllGlobals());
 
+  const noCopy = async () => false;
+
   function stubDownloadEnv(canShare: boolean, share: () => Promise<void>) {
     const anchor = { href: '', download: '', click: vi.fn(), remove: vi.fn() };
     const createElement = vi.fn(() => anchor);
@@ -45,20 +50,37 @@ describe('shareOrDownloadGcg', () => {
     const share = vi.fn().mockRejectedValue(new DOMException('cancelled', 'AbortError'));
     const { createElement } = stubDownloadEnv(true, share);
 
-    await shareOrDownloadGcg(gcg);
+    expect(await shareOrDownloadGcg(gcg, false, noCopy)).toBe('shared');
 
     expect(share).toHaveBeenCalledOnce();
     expect(createElement).not.toHaveBeenCalled(); // no download anchor → no webview navigation
   });
 
-  it('downloads via an anchor when the platform cannot share files', async () => {
+  it('downloads via an anchor on a desktop browser that cannot share files', async () => {
     const { anchor, createElement } = stubDownloadEnv(false, vi.fn());
 
-    await shareOrDownloadGcg(gcg);
+    expect(await shareOrDownloadGcg(gcg, false, noCopy)).toBe('downloaded');
 
     expect(createElement).toHaveBeenCalledWith('a');
     expect(anchor.click).toHaveBeenCalledOnce();
   });
+
+  it('copies to the clipboard in an in-app webview that cannot share files (no dead Blob download)', async () => {
+    // Android Telegram/VK expose no Web Share AND ignore <a download>, so the export must copy the
+    // GCG text instead of silently issuing an anchor click that does nothing.
+    const copy = vi.fn().mockResolvedValue(true);
+    const { createElement } = stubDownloadEnv(false, vi.fn());
+
+    expect(await shareOrDownloadGcg(gcg, true, copy)).toBe('copied');
+
+    expect(copy).toHaveBeenCalledWith(gcg.content);
+    expect(createElement).not.toHaveBeenCalled();
+  });
+
+  it('reports failure when the in-app clipboard copy fails', async () => {
+    stubDownloadEnv(false, vi.fn());
+    expect(await shareOrDownloadGcg(gcg, true, async () => false)).toBe('failed');
+  });
 });
 
 describe('pickTextShare', () => {