feat: add AI学习助手 agent (KG+RAG ideal) and renshenguo feishu bot

- Add AI学习助手 agent creation script with all 39 tools, 3-layer KG+RAG memory
- Add renshenguo (人参果) feishu bot integration (app_service + ws_handler)
- Register renshenguo WS client in main.py startup
- Add RENSHENGUO_APP_ID / RENSHENGUO_APP_SECRET / RENSHENGUO_AGENT_ID config
- Reorganize docs from root into docs/ subdirectories
- Move startup scripts to scripts/startup/
- Various backend optimizations and tool improvements

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

misc/test-data/test_emails.txt

@@ -0,0 +1,27 @@
+user@example.com
+first.last@example.com
+user+tag@example.co.uk
+user_name@example.org
+user%name@example.com
+123456@example.cn
+a@b.co
+nice&simple@example.com
+very.common@example.com
+disposable.style.email.with+symbol@example.com
+other.email-with-hyphen@example.com
+fully-qualified-domain@example.com
+user.name+tag+sorting@example.com
+x@example.com
+example-indeed@strange-example.com
+
+plainaddress
+@no-local-part.com
+user@.com
+user@com
+user@domain..com
+user@-domain.com
+user@domain.com.
+user name@example.com
+user@domain,com
+user@domain.c
+user@.domain.com