feat(telegram): send fresh finals for stale preview streams (port openclaw#72038) (#16261)

Ports openclaw/openclaw#72038 to hermes-agent.

Telegram's `editMessageText` preserves the original message timestamp,
so a long-running streamed reply (reasoning models that take 60+ seconds
to finish) would keep the first-token timestamp even after completion.
Users can't tell how long a task actually took.

When a preview message has been visible for >= 60s (configurable via
`streaming.fresh_final_after_seconds`), finalize by sending a fresh
message instead of editing in place, then best-effort delete the stale
preview. Short previews still edit in place (the existing fast path).

Implementation notes adapted from OpenClaw's TypeScript original:
- `StreamConsumerConfig` gains `fresh_final_after_seconds` (default 0 =
  legacy edit-in-place). Gateway-level `StreamingConfig` defaults to 60.
- `GatewayStreamConsumer` tracks `_message_created_ts` at first-send and
  checks it in `_send_or_edit` on `finalize=True`. New helpers
  `_should_send_fresh_final` + `_try_fresh_final`.
- `BasePlatformAdapter` gains optional `delete_message(chat_id, message_id)`
  returning False by default. `TelegramAdapter` implements it via
  `_bot.delete_message`.
- `gateway/run.py` only enables fresh-final for `Platform.TELEGRAM`;
  other platforms ignore the setting (they don't have the stale-edit
  timestamp problem or edit-then-read works cheaply).
- Fallback to normal edit on any fresh-send failure — no user-visible
  regression if Telegram rate-limits a send or the message is gone.

Tests: 15 new cases in tests/gateway/test_stream_consumer_fresh_final.py
covering short/long previews, config plumbing, delete-support absent,
send-failure fallback, __no_edit__ sentinel safety, and StreamingConfig
round-trip.

Co-authored-by: Hermes Agent <agent@nousresearch.com>

website/docs/user-guide/configuration.md

@@ -1114,6 +1114,7 @@ streaming:
   edit_interval: 0.3      # Seconds between message edits
   buffer_threshold: 40    # Characters before forcing an edit flush
   cursor: " ▉"            # Cursor shown during streaming
+  fresh_final_after_seconds: 60   # Send fresh final (Telegram) when preview is this old; 0 = always edit in place
 ```
 
 When enabled, the bot sends a message on the first token, then progressively edits it as more tokens arrive. Platforms that don't support message editing (Signal, Email, Home Assistant) are auto-detected on the first attempt — streaming is gracefully disabled for that session with no flood of messages.
@@ -1122,6 +1123,8 @@ For separate natural mid-turn assistant updates without progressive token editin
 
 **Overflow handling:** If the streamed text exceeds the platform's message length limit (~4096 chars), the current message is finalized and a new one starts automatically.
 
+**Fresh final (Telegram):** Telegram's `editMessageText` preserves the original message timestamp, so a long-running streamed reply would keep the first-token timestamp even after completion. When `fresh_final_after_seconds > 0` (default `60`), the completed reply is delivered as a brand-new message (with the stale preview best-effort deleted) so Telegram's visible timestamp reflects completion time. Short previews still finalize in place. Set to `0` to always edit in place.
+
 :::note
 Streaming is disabled by default. Enable it in `~/.hermes/config.yaml` to try the streaming UX.
 :::