feat: decouple manual image sharing from automation gating

The "Share a saved image" panel was wired to the automated exchange
engine, so an operator could only share an image right after an inbound
image request, limited to assets the auto-exchanger would itself pick.

Add a manual path that offers any enabled, unused library image at any
point (no request detection, tier, seller, or boundary gating) and sends
it with no reciprocal "your turn" text. Safety flags now surface as a
non-blocking warning instead of disabling the panel. The automated
auto-send path keeps all its guardrails; the shared image-delivery step
is extracted into a helper used by both paths.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/media-library-exchange.test.ts

@@ -129,6 +129,49 @@ describe('MediaLibraryExchangeService', () => {
     expect(chat.sendChatMessage).toHaveBeenCalledOnce();
     db.close();
   });
+
+  it('manually shares any enabled image with no request gating and no reciprocal text', async () => {
+    const db = createTestDb();
+    const repository = new MediaLibraryRepository(db);
+    await addAsset(repository, directory, 'selfie', ['selfie'], 'sfw', 1);
+    await addAsset(repository, directory, 'topless', ['topless'], 'nsfw', 2);
+    const chat = {
+      sendChatImage: vi.fn().mockResolvedValue({ eventId: '$img', mxcUri: 'mxc://img' }),
+      sendChatMessage: vi.fn().mockResolvedValue(true),
+    };
+    const service = new MediaLibraryExchangeService(repository, chat, logger(), 'account', directory);
+
+    // No image request in the conversation, yet every enabled image is offered.
+    expect(service.listShareableManual('room').map((asset) => asset.id).sort()).toEqual(['selfie', 'topless']);
+
+    const result = await service.shareManual('room', 'topless');
+    expect(result).toMatchObject({ kind: 'sent', assetId: 'topless' });
+    expect(chat.sendChatImage).toHaveBeenCalledOnce();
+    expect(chat.sendChatMessage).not.toHaveBeenCalled();
+
+    // The shared image leaves the manual list; re-sharing it is idempotent and re-sends nothing.
+    expect(service.listShareableManual('room').map((asset) => asset.id)).toEqual(['selfie']);
+    expect(await service.shareManual('room', 'topless')).toMatchObject({ kind: 'sent', assetId: 'topless' });
+    expect(chat.sendChatImage).toHaveBeenCalledOnce();
+    db.close();
+  });
+
+  it('refuses a manual share of an unknown or disabled image', async () => {
+    const db = createTestDb();
+    const repository = new MediaLibraryRepository(db);
+    await addAsset(repository, directory, 'selfie', ['selfie'], 'sfw', 1);
+    repository.update('selfie', ['selfie'], 'sfw', false);
+    const chat = {
+      sendChatImage: vi.fn().mockResolvedValue({ eventId: '$img', mxcUri: 'mxc://img' }),
+      sendChatMessage: vi.fn().mockResolvedValue(true),
+    };
+    const service = new MediaLibraryExchangeService(repository, chat, logger(), 'account', directory);
+
+    expect(await service.shareManual('room', 'does-not-exist')).toMatchObject({ kind: 'human-required' });
+    expect(await service.shareManual('room', 'selfie')).toMatchObject({ kind: 'human-required' });
+    expect(chat.sendChatImage).not.toHaveBeenCalled();
+    db.close();
+  });
 });
 
 async function addAsset(