Add Telegram Bot API 10.1 rich message support

Introduce opportunistic support for Telegram Bot API 10.1 rich messages by sending raw agent Markdown via sendRichMessage and streaming previews via sendRichMessageDraft. Implements a rich-path fast‑path in gateway/platforms/telegram.py (RICH_MESSAGE_MAX_BYTES=32768, feature gate platforms.telegram.extra.rich_messages, bot capability checks, routing/thread handling, and conservative fallback rules: permanent/capability errors fall back to the legacy MarkdownV2 path, transient/network errors are surfaced without legacy-resend). Also add a latch for draft capability failures (_rich_draft_disabled) and preserve legacy chunking and draft behavior when needed. Update agent prompt hints (telegram encourages rich Markdown/tables), add CLI config example option, update English and Chinese docs to describe rich messages and fallbacks, and add/adjust tests for rich send and draft behavior.

cli-config.yaml.example

@@ -719,6 +719,10 @@ platform_toolsets:
 #     # allowed_chats: ["-1001234567890"]
 #     extra:
 #       disable_link_previews: false  # Set true to suppress Telegram URL previews in bot messages
+#       # Bot API 10.1 Rich Messages: final replies send raw markdown via
+#       # sendRichMessage so tables, task lists, collapsible details, math, etc.
+#       # render natively (with automatic MarkdownV2 fallback). Default true.
+#       rich_messages: true  # Set false to force the legacy MarkdownV2 path
 #
 # Discord-specific settings (config.yaml top-level, not under platforms:):
 #