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>

bot/src/db/queries.ts

@@ -115,9 +115,15 @@ export async function getPendingSendRequest(requestId: string) {
         select: {
           id: true,
           fileName: true,
+          fileSize: true,
+          fileCount: true,
+          creator: true,
+          tags: true,
+          archiveType: true,
           destChannelId: true,
           destMessageId: true,
           previewData: true,
+          sourceChannel: { select: { title: true, telegramId: true } },
         },
       },
       telegramLink: true,