#11340: Telegram: skip empty message text instead of throwing (#11238)

## Fix The Telegram adapter throws an error when `sendMessageTelegram` receives empty or whitespace-only text, which Telegram rejects with `400: Bad Request: message text is empty`. This causes silent failures across multiple codepaths (final reply, heartbeat, agent delivery) with **94 occurrences** reported over ~19 hours. **Root cause:** `sendMessageTelegram` threw `Error("Message must be non-empty for Telegram sends")` for empty text. Callers (heartbeat responses, interrupted inference results, auth profile cooldown) sometimes produce empty text legitimately, and the throw propagated as an unhandled error. ## Changes - `src/telegram/send.ts`: Replace `throw` with a warning log + safe no-op return (`{ messageId: "skipped", chatId }`) for empty/whitespace text - `src/telegram/send.returns-undefined-empty-input.test.ts`: Add 2 regression tests (empty string, whitespace-only) - `CHANGELOG.md`: Add entry ## Verification - `pnpm build` passes - All 33 telegram send tests pass (`npx vitest run src/telegram/send.returns-undefined-empty-input.test.ts`) - New tests confirm empty and whitespace-only text returns `{ messageId: "skipped", chatId }` without calling `api.sendMessage` Fixes #11238 <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This change updates the Telegram adapter’s `sendMessageTelegram` to treat empty or whitespace-only message text as a safe no-op: it logs a diagnostic warning and returns `{ messageId: "skipped", chatId }` rather than throwing. Regression tests were added to ensure empty/whitespace text does not call `api.sendMessage`, and the changelog documents the fix. Overall this aligns Telegram behavior with other channel senders that treat empty content as “skipped”, preventing unhandled exceptions from bubbling through higher-level delivery paths. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - The change is narrowly scoped (empty/whitespace text handling), adds targeted regression tests, and follows an existing pattern by other channel senders (returning a "skipped" result instead of throwing). No other logic paths were altered. - No files require special attention <!-- greptile_other_comments_section --> **Context used:** - Context from `dashboard` - CLAUDE.md ([source](https://app.greptile.com/review/custom-context?memory=fd949e91-5c3a-4ab5-90a1-cbe184fd6ce8)) - Context from `dashboard` - AGENTS.md ([source](https://app.greptile.com/review/custom-context?memory=0d0c8278-ef8e-4d6c-ab21-f5527e322f13)) <!-- /greptile_comment -->