feat: add custom endpoint domain support for HCSO/on-premise deployments

[filhocf]

Summary

Adds support for custom endpoint domains, enabling the MCP server to work with Huawei Cloud Stack Online (HCSO) and other on-premise deployments where the default myhuaweicloud.com domain is not reachable.

Closes #137

Problem

The current implementation hardcodes endpoints to *.myhuaweicloud.com. In HCSO on-premise environments, API endpoints use a different domain (e.g., *.hcso.customer-domain.com), making the MCP server unusable.

Changes

assets/utils/variable.py

• Added HUAWEI_ENDPOINT_DOMAIN environment variable constant

assets/utils/model.py

• Added endpoint_domain: Optional[str] field to MCPConfig dataclass

assets/utils/hwc_tools.py

• Modified create_api_client() to accept endpoint_domain parameter
• When endpoint_domain is set, replaces myhuaweicloud.com with the custom domain
• Improved URL scheme detection (uses \".\" in endpoint instead of \"com\" in endpoint)
• Added HUAWEI_ENDPOINT_DOMAIN to env variable mapping in load_config()

assets/utils/server.py

• Passes self.config.endpoint_domain to create_api_client() in the tool handler

Usage

Via environment variable (recommended)

export HUAWEI_ENDPOINT_DOMAIN=\"hcso.customer-domain.com\"
uv run mcp-server-ecs -t stdio
# Endpoints become: https://ecs.{region}.hcso.customer-domain.com

Via config.yaml

service_code: ecs
transport: stdio
endpoint_domain: hcso.customer-domain.com

MCP client configuration (Kiro/Cursor/Cline)

{
  \"mcpServers\": {
    \"huawei-ecs\": {
      \"command\": \"uv\",
      \"args\": [\"run\", \"--directory\", \"/path/to/mcp-server\", \"mcp-server-ecs\", \"-t\", \"stdio\"],
      \"env\": {
        \"HUAWEI_ACCESS_KEY\": \"...\",
        \"HUAWEI_SECRET_KEY\": \"...\",
        \"HUAWEI_ENDPOINT_DOMAIN\": \"hcso.customer-domain.com\"
      }
    }
  }
}

Backward Compatibility

• No breaking changes. When endpoint_domain is not set, behavior is identical to before.
• Environment variable takes precedence over config.yaml value.