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/operations/troubleshooting.md

@@ -0,0 +1,46 @@
+# Troubleshooting
+
+## Service Not Reachable
+
+Check service status:
+
+```bash
+systemctl status clicd
+journalctl -u clicd -n 100 --no-pager
+```
+
+Check port listening:
+
+```bash
+ss -lntp | grep 8999
+```
+
+If a reverse proxy is used, check proxy logs and upstream address settings as well.
+
+## Image Download Failed
+
+- Make sure the host can access image sources and GitHub Releases.
+- Check disk space.
+- Review the failure reason in the task queue.
+- If a download is stuck, cancel it and start again.
+
+## Container Cannot Access the Network
+
+- Check host NAT and forwarding rules.
+- Confirm that the container IP was assigned successfully.
+- Check whether the firewall is blocking forwarded traffic.
+- For IPv6, confirm that the upstream network routes the prefix to the host.
+
+## WebSSH or WebVNC Connection Failed
+
+- Confirm that the container or virtual machine is running.
+- WebSSH requires SSH service inside the container.
+- WebVNC requires the KVM console to be reachable.
+- Tickets expire quickly. Create a new ticket after expiration.
+
+## API Returns Unauthorized
+
+- Confirm that the API key is not disabled.
+- Use `X-API-Key` or `Authorization: Bearer`.
+- Confirm that the key scope covers the target endpoint.
+- Do not use the panel login password as an API key.