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/recipient-account-status.test.ts

@@ -0,0 +1,62 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import Database from 'better-sqlite3';
+import { RedditRecipientAccountStatusRepository } from '../src/database/account-repositories.js';
+import { runMigrations } from '../src/database/client.js';
+import { RecipientAccountStatusService } from '../src/services/recipient-account-status.js';
+import { createMockLogger } from './mockLogger.js';
+
+describe('RecipientAccountStatusService', () => {
+  let db: Database.Database;
+
+  beforeEach(() => {
+    db = new Database(':memory:');
+    runMigrations(db);
+  });
+
+  afterEach(() => db.close());
+
+  it('checks each real username once, persists results, and skips fresh checks', async () => {
+    let now = 10_000;
+    const repository = new RedditRecipientAccountStatusRepository(db);
+    const lookup = {
+      getUserAccountStatus: vi.fn(async (username: string) => username === 'Alice' ? 'deleted' as const : 'active' as const),
+    };
+    const service = new RecipientAccountStatusService(
+      {
+        getCachedConversations: vi.fn(async () => [
+          { username: 'Alice' }, { username: 'alice' }, { username: 'Bob' },
+          { username: 'unknown' }, { username: 't2_abc' },
+        ]),
+      } as never,
+      lookup,
+      repository,
+      createMockLogger(),
+      { isFullyAuthenticated: () => true, invalidate: () => undefined },
+      4_000,
+      () => now,
+    );
+
+    await expect(service.checkNow()).resolves.toBe(2);
+    expect(lookup.getUserAccountStatus).toHaveBeenCalledTimes(2);
+    expect(repository.get('alice')).toMatchObject({ status: 'deleted', checkedAt: 10_000 });
+
+    now = 12_000;
+    await expect(service.checkNow()).resolves.toBe(0);
+    now = 15_000;
+    await expect(service.checkNow()).resolves.toBe(2);
+  });
+
+  it('does no profile work while account authentication is unavailable', async () => {
+    const lookup = { getUserAccountStatus: vi.fn() };
+    const service = new RecipientAccountStatusService(
+      { getCachedConversations: vi.fn() } as never,
+      lookup,
+      new RedditRecipientAccountStatusRepository(db),
+      createMockLogger(),
+      { isFullyAuthenticated: () => false, invalidate: () => undefined },
+    );
+
+    await expect(service.checkNow()).resolves.toBe(0);
+    expect(lookup.getUserAccountStatus).not.toHaveBeenCalled();
+  });
+});