fix(telegram): file round-trip + clickable permission prompts (#84)

[chauncygu]

Two missing code paths in bridges/telegram.py produced both halves of issue #84: the bridge had only _tg_send (text via sendMessage), so (1) the agent claimed to "send a file" but only emitted text — even with --accept-all there was no sendDocument helper, no inbound document handler, and no path for the agent to emit a file; and (2) permission prompts arrived as text containing [y/N/a(ccept-all)] that looked like buttons but weren't, because the poll loop only listened for message updates and there was no inline-keyboard render.

bridges/telegram.py

• _tg_send_document(token, chat_id, file_path, caption=None) — manual multipart/form-data upload, 49 MB cap (Telegram hard limit is 50 MB; headroom for encoding overhead). Six failure modes report specific errors to chat: missing, stat failure, empty, oversize, network exception, API ok=false.
• Inbound document handler in tg_poll_loop — getFile download, filename sanitized to [A-Za-z0-9.-]_, saved to /workspace if mounted else tempfile.gettempdir(), path echoed to chat, then a path-aware prompt submitted to the agent (caption-overridable).
• !sendfile <absolute_path> user command — explicit on-demand send in a daemon thread so the poll loop does not block.
• Auto-send on Write — _on_tool_start records the in-flight file_path; _on_tool_end mails it (FIFO-paired). Skipped on Error: / Denied: results, de-duplicated per turn via _sent_files.
• _tg_send_keyboard(...) — sendMessage with reply_markup inline_keyboard. Three-layer fallback: Markdown -> no parse_mode same keyboard -> plain text no keyboard.
• _handle_callback_query(...) — extracted for testability. Auth check (chat_id), answerCallbackQuery to clear click spinner, prompt_id validation (stale clicks dropped silently), editMessageText appends "✓ Selected: " for scroll-back, fires tg_input_event with the value to unblock the agent.
• Poll loop allowed_updates widened to ["message", "callback_query"].

tools/interaction.py

• ask_input_interactive grows options=[(label, value), ...] parameter. Telegram branch renders inline_keyboard when options non-empty; Slack / WeChat / terminal ignore options and keep using the text path. Event + prompt_id are registered before the keyboard send so a fast click cannot race in.

cheetahclaws.py

• ask_permission_interactive passes [("✅ Approve","y"), ("❌ Reject","n"), ("✅✅ Accept all","a")].

runtime.py

• RuntimeContext adds tg_callback_prompt_id: str and tg_callback_message_id: int.

tests/test_telegram_bridge.py

• 27 new pytest cases. urllib.request.urlopen and _tg_api are mocked; threading.Thread is monkeypatched to a synchronous stub for the auto-send hook; an end-to-end test drives ask_input_interactive(options=...) from a worker thread, simulates a click via _handle_callback_query, and asserts the worker returns the clicked value.

docs/guides/bridges.md, docs/news.md, README.md, docs/README.CN.MD

• New "Permission prompts (clickable buttons)" and "File support" sections; news entry covering both halves of Telegram bridge cannot send files/documents even with --accept-all #84.

Tests: 696 passed in 43s (was 669 before this change).