chore: 清理根目录冗余文件（旧文档/启动脚本/配置等）

删除: FEATURE_SUMMARY.md / QUICK_START.md / STARTUP.md
       INTERNAL_DEPLOYMENT_GUIDE.md / INTERNAL_DEPLOYMENT_SUMMARY.md
       start-server.bat / start-web.bat / .dockerignore

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.codegraph/.gitignore

@@ -0,0 +1,16 @@
+# CodeGraph data files
+# These are local to each machine and should not be committed
+
+# Database
+*.db
+*.db-wal
+*.db-shm
+
+# Cache
+cache/
+
+# Logs
+*.log
+
+# Hook markers
+.dirty