Refactor: split services.py into services/ package

ChatService → services/chat.py
DocumentService → services/document.py
TTSService → services/tts.py
services/__init__.py re-exports all three for backward-compatible imports

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

.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>