feat: add deep think feature (#311)

* feat: implement backend logic

* feat: implement api/config endpoint

* rename the symbol

* feat: re-implement configuration at client-side

* feat: add client-side of deep thinking

* fix backend bug

* feat: add reasoning block

* docs: update readme

* fix: translate into English

* fix: change icon to lightbulb

* feat: ignore more bad cases

* feat: adjust thinking layout, and implement auto scrolling

* docs: add comments

---------

Co-authored-by: Henry Li <henry1943@163.com>

.gitignore

@@ -6,6 +6,7 @@ dist/
 wheels/
 *.egg-info
 .coverage
+.coverage.*
 agent_history.gif
 static/browser_history/*.gif