refactor: move Telegram channel implementation to extensions/ (#45635)

* refactor: move Telegram channel implementation to extensions/telegram/src/

Move all Telegram channel code (123 files + 10 bot/ files + 8 channel plugin
files) from src/telegram/ and src/channels/plugins/*/telegram.ts to
extensions/telegram/src/. Leave thin re-export shims at original locations so
cross-cutting src/ imports continue to resolve.

- Fix all relative import paths in moved files (../X/ -> ../../../src/X/)
- Fix vi.mock paths in 60 test files
- Fix inline typeof import() expressions
- Update tsconfig.plugin-sdk.dts.json rootDir to "." for cross-directory DTS
- Update write-plugin-sdk-entry-dts.ts for new rootDir structure
- Move channel plugin files with correct path remapping

* fix: support keyed telegram send deps

* fix: sync telegram extension copies with latest main

* fix: correct import paths and remove misplaced files in telegram extension

* fix: sync outbound-adapter with main (add sendTelegramPayloadMessages) and fix delivery.test import path

extensions/telegram/src/proxy.ts

@@ -0,0 +1 @@
+export { getProxyUrlFromFetch, makeProxyFetch } from "../../../src/infra/net/proxy-fetch.js";