Describe your changes

• Add a Telegram-scoped block reply break override so blockStreaming: true uses message_end boundaries.
• Propagate the break override through reply directives to embedded runs via GetReplyOptions.blockReplyBreak.
• Keep existing global defaults intact while ensuring Telegram can emit intermediate assistant messages on providers that do not emit text_end events.
• Add regression coverage for helper resolution, Telegram dispatch reply options, and end-to-end propagation into embedded run params.

Screenshot or video (only for visual changes)

• N/A

GitHub Issue Link (if applicable)

• Telegram channel with blockStreaming: true drops messages #16604

Testing Plan

• Explanation of why no additional tests are needed: Added focused automated tests covering option resolution and propagation paths.
• Unit Tests (JS and/or Python): pnpm test src/telegram/bot/helpers.test.ts src/telegram/bot-message-dispatch.test.ts src/auto-reply/reply.block-streaming.test.ts
• E2E Tests: Included via the targeted block-streaming test suite above.
• Any manual testing needed?: Optional: configure Telegram with streamMode: "off" and blockStreaming: true, then verify multi-message turns deliver each assistant message sequentially.

Contribution License Agreement
By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.