feat: recover missing conversations, fix media attachment, add manual inbox tab

Missing conversations: recipient Reddit accounts that are deleted or suspended
left conversations unaccounted for. A new RecipientAccountStatusService polls
Reddit for the users behind cached conversations and records their account
status durably, with progressive backfill and delta-media fixes in ChatService
so history and images are no longer dropped mid-sync.

Media: attachMedia now surfaces download failures as MediaAttachmentError so the
sync cursor can be retried instead of silently losing an image, recognizes image
bytes when Matrix returns a generic content type, and keeps separate gallery
occurrences when the same asset appears in more than one event.

Manual inbox tab: the conversations list now carries the reply-loop status, so
the inbox can separate conversations the operator is driving by hand from the
ones automation is still handling. A Manual filter pill and a per-row chip
explain why each conversation was handed over.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/reddit-api.test.ts

@@ -540,6 +540,36 @@ describe('RedditApiClient', () => {
     });
   });
 
+  describe('getUserAccountStatus', () => {
+    it('distinguishes active, suspended and deleted accounts', async () => {
+      const mockAxios = { get: vi.fn() };
+      vi.mocked(axios.create).mockReturnValue(mockAxios as unknown as AxiosInstance);
+      const client2 = new RedditApiClient(getTestConfig(), logger);
+
+      mockAxios.get.mockResolvedValueOnce({ data: { data: {} } });
+      await expect(client2.getUserAccountStatus('active-user')).resolves.toBe('active');
+
+      mockAxios.get.mockResolvedValueOnce({ data: { data: { is_suspended: true } } });
+      await expect(client2.getUserAccountStatus('suspended-user')).resolves.toBe('suspended');
+
+      mockAxios.get.mockRejectedValueOnce({ isAxiosError: true, response: { status: 404 } });
+      await expect(client2.getUserAccountStatus('deleted-user')).resolves.toBe('deleted');
+    });
+
+    it('does not turn temporary or malformed responses into deletion signals', async () => {
+      const mockAxios = { get: vi.fn() };
+      vi.mocked(axios.create).mockReturnValue(mockAxios as unknown as AxiosInstance);
+      const client2 = new RedditApiClient(getTestConfig(), logger);
+
+      const temporary = { isAxiosError: true, response: { status: 503 } };
+      mockAxios.get.mockRejectedValueOnce(temporary);
+      await expect(client2.getUserAccountStatus('alice')).rejects.toBe(temporary);
+
+      mockAxios.get.mockResolvedValueOnce({ data: {} });
+      await expect(client2.getUserAccountStatus('alice')).rejects.toThrow();
+    });
+  });
+
   describe('getNewPosts', () => {
     it('throws a permanent-disable signal for a plain 404 subreddit', async () => {
       const error = { isAxiosError: true, response: { status: 404 } };