feat(streaming): centralize think-tag filtering and add Telegram streaming

- Add strip_think() to helpers.py as single source of truth
- Filter deltas in agent loop before dispatching to consumers
- Implement send_delta in TelegramChannel with progressive edit_message_text
- Remove duplicate think filtering from CLI stream.py and telegram.py
- Remove legacy fake streaming (send_message_draft) from Telegram
- Default Telegram streaming to true
- Update CHANNEL_PLUGIN_GUIDE.md with streaming documentation

Made-with: Cursor

nanobot/utils/helpers.py

@@ -11,6 +11,13 @@ from typing import Any
 import tiktoken
 
 
+def strip_think(text: str) -> str:
+    """Remove <think>…</think> blocks and any unclosed trailing <think> tag."""
+    text = re.sub(r"<think>[\s\S]*?</think>", "", text)
+    text = re.sub(r"<think>[\s\S]*$", "", text)
+    return text.strip()
+
+
 def detect_image_mime(data: bytes) -> str | None:
     """Detect image MIME type from magic bytes, ignoring file extension."""
     if data[:8] == b"\x89PNG\r\n\x1a\n":