feat: support all chat types in channel discovery and enrich bot messages

Channel Discovery:
- Remove channel/supergroup filter from getAccountChats — all chat types
  (private, groups, Saved Messages, etc.) are now discoverable as sources
- Detect and label the self-chat as "Saved Messages" via getMe
- Update channel picker dialog to accept any chat type string

Bot Rich Messages:
- Enhance package send preview with creator, file count, tags, and source
  channel info in MarkdownV2 caption
- Include tags in new_package subscription notifications
- Expand getPendingSendRequest to fetch richer package data

Performance:
- Reviewed pipeline for many-channel load — getChats pagination fix and
  per-channel getChat pre-load from prior commit address the main concerns
- Channels with no new messages skip in 2-3 API calls

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/(app)/telegram/_components/channel-picker-dialog.tsx

@@ -21,7 +21,7 @@ import { ScrollArea } from "@/components/ui/scroll-area";
 interface FetchedChannel {
   chatId: string;
   title: string;
-  type: "channel" | "supergroup";
+  type: string;
   isForum: boolean;
   memberCount: number | null;
   alreadyLinked: boolean;