feat: Round 5 - Memory Service, Tool Engine, Call Records, Thinking Logs

- Fix: Session history flash (race condition + WS guard)
- Fix: Chat background overlay + sidebar transparency
- Fix: IoT device control (Chinese action names, status field)
- Feat: Independent memory-service (port 8091, 13 endpoints)
- Feat: Independent tool-engine service (port 8092, 13 tools)
- Feat: Tool call logs with paginated DevTools panel
- Feat: Thinking log records with DevTools panel
- Feat: Future development roadmap document
- Chore: Updated .gitignore, go.work, DevTools config
- Chore: 5-service health check, project review docs

.gitignore

@@ -19,6 +19,13 @@ devtools/package-lock.json
 
 # Go 编译二进制
 backend/ai-core/main
+backend/ai-core/cmd/main
 backend/gateway/main
-backend/cmd
-backend/iot-debug-service/main
+backend/gateway/cmd/main
+backend/iot-debug-service/main
+backend/iot-debug-service/cmd/main
+backend/memory-service/cmd/main
+backend/tool-engine/cmd/tool-engine
+
+# Stale binary (old build artifact)
+backend/cmd