Add comprehensive documentation for CLICD features and operations

- Introduced Container Management documentation covering lifecycle operations, resource management, and console access.
- Added Dashboard documentation detailing metrics and related APIs.
- Created Host Report documentation summarizing host environment and resource status.
- Included Image Management documentation for template handling and management actions.
- Documented Networking and Routing features including NAT4 and IPv6 management.
- Added Security Alerts documentation outlining alert scenarios and API usage.
- Created Snapshot Management documentation for snapshot operations and scheduling.
- Documented Sub-user management for granting access to specific containers.
- Added Configuration guide detailing runtime settings and security recommendations.
- Created Installation guide for setting up CLICD with requirements and steps.
- Added Introduction and Quick Start guides for new users.
- Documented Upgrade process with version checking and pre-upgrade checklist.
- Created Deployment guide for service exposure and firewall recommendations.
- Added FAQ section addressing common questions and concerns.
- Documented Troubleshooting steps for common issues encountered.

docs/en/developer/architecture.md

@@ -0,0 +1,42 @@
+# Architecture
+
+CLICD consists of a Go backend, a React frontend, and host virtualization capabilities.
+
+## Backend
+
+The backend entry point is `backend/main.go`, and HTTP routes are centralized in `backend/internal/server/server.go`. Main modules:
+
+- `internal/api`: HTTP APIs for the web panel and `/api/v1`.
+- `internal/config`: configuration and SQLite storage.
+- `internal/lxc`: LXC container management.
+- `internal/kvm`: KVM/libvirt virtual machine management.
+- `internal/cli`: command-line management entry point.
+- `internal/server`: embedded frontend assets and HTTP service.
+- `internal/version`: version number.
+
+## Frontend
+
+The frontend entry point is `frontend/src/main.tsx`. Pages live in `frontend/src/pages`, and shared components live in `frontend/src/components`.
+
+Main pages:
+
+- Dashboard: `Dashboard.tsx`
+- Container list: `Containers.tsx`
+- Container details: `ContainerDetail.tsx`
+- Image Management: `ImageManagement.tsx`
+- Security Alerts: `Security.tsx`
+- Snapshot Management: `Snapshots.tsx`
+- Routing Management: `Routing.tsx`
+- API Integration: `ApiIntegration.tsx`
+- Host Report: `HostReport.tsx`
+- Sub-user Management: `SubUserManagement.tsx`
+
+## Frontend Embedding
+
+For production builds, frontend artifacts are placed in `backend/internal/server/web`. The backend serves them through Go embed and returns the SPA entry for non-API routes.
+
+## API Layers
+
+- `/api/*`: web panel and compatibility APIs.
+- `/api/v1/*`: versioned APIs recommended for external automation.
+- WebSSH and WebVNC use short-lived tickets before opening WebSocket connections.