#17723: Telegram actions: let poll fall back to core sender

## Summary - prevent Telegram plugin adapter from intercepting unsupported actions like `poll` - add an explicit Telegram plugin action whitelist via `supportsAction` - allow `poll` to correctly fall back to the core outbound `sendPoll` path instead of throwing `Action poll is not supported for provider telegram` - add regression coverage in `actions.test.ts` ## Testing - bunx vitest run src/channels/plugins/actions/actions.test.ts - bunx oxlint --type-aware src/channels/plugins/actions/telegram.ts src/channels/plugins/actions/actions.test.ts - bunx oxfmt --check src/channels/plugins/actions/telegram.ts src/channels/plugins/actions/actions.test.ts Fixes #17528 <!-- greptile_comment --> <h3>Greptile Summary</h3> Adds explicit action support filtering to the Telegram plugin adapter to prevent it from intercepting unsupported actions like `poll`. The `supportsAction` method now uses a whitelist (`TELEGRAM_PLUGIN_ACTIONS`) containing only the actions this adapter can handle: `send`, `react`, `delete`, `edit`, `sticker`, and `sticker-search`. This allows `poll` actions to correctly fall back to the core outbound `sendPoll` path instead of throwing an error. - Added `TELEGRAM_PLUGIN_ACTIONS` Set with supported action names - Implemented `supportsAction` method on the Telegram adapter - Added regression test coverage verifying `send` is supported and `poll` is not - Follows existing pattern used by Signal adapter <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with no risk - The change is minimal, well-tested, and follows established patterns. It adds an explicit whitelist to prevent incorrect action routing, which is a defensive programming practice. The implementation is straightforward with appropriate test coverage, and fixes a clear bug where unsupported actions were being intercepted. - No files require special attention _{Last reviewed commit: 1d63547} <!-- greptile_other_comments_section --> _{(3/5) Reply to the agent's comments like "Can you suggest a fix for this @greptileai?" or ask follow-up questions!} <!-- /greptile_comment -->