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>

src/reddit/api.ts

@@ -1,5 +1,6 @@
 import axios, { AxiosInstance } from 'axios';
 import type { BrowserContext } from 'playwright';
+import { z } from 'zod';
 import type { Config } from '../config/index.js';
 import type { Logger } from '../utils/logger.js';
 import type { RedditRequestScheduler } from './request-coordinator.js';
@@ -9,6 +10,14 @@ const uncoordinatedRequestScheduler: RedditRequestScheduler = {
   extendCooldown: () => undefined,
 };
 
+const RedditUserAboutResponseSchema = z.object({
+  data: z.object({
+    is_suspended: z.boolean().optional(),
+  }),
+});
+
+export type RedditUserAccountStatus = 'active' | 'suspended' | 'deleted';
+
 export class RedditRateLimitError extends Error {
   constructor(public readonly retryAfterMs: number) {
     const retryAfterSeconds = Math.ceil(retryAfterMs / 1000);
@@ -197,6 +206,27 @@ export class RedditApiClient {
     }
   }
 
+  /** A 404 is Reddit's definitive signal that the username no longer has an account. */
+  async getUserAccountStatus(username: string): Promise<RedditUserAccountStatus> {
+    const cookieHeader = await this.getCookieHeader();
+    const headers: Record<string, string> = {};
+    if (cookieHeader) headers.Cookie = cookieHeader;
+
+    try {
+      const response = await this.scheduleRequest(() => this.client.get(
+        `/user/${encodeURIComponent(username)}/about.json`,
+        { params: { raw_json: 1 }, headers },
+      ));
+      const parsed = RedditUserAboutResponseSchema.parse(response.data);
+      return parsed.data.is_suspended === true ? 'suspended' : 'active';
+    } catch (error) {
+      if (axios.isAxiosError(error) && error.response?.status === 404) return 'deleted';
+      const rateLimitError = this.toRateLimitError(error);
+      if (rateLimitError) throw rateLimitError;
+      throw error;
+    }
+  }
+
   async getNewPosts(subreddit: string, limit = 25, type: 'image' | 'chat' = 'image'): Promise<RedditPost[]> {
     try {
       const cookieHeader = await this.getCookieHeader();