Complete PHP MCP client and Docker Compose stdio bridge

[Llewellynvdm]

Why

Let an AI application connect to an installed Joomla MCP component using only its HTTPS site URL and native Joomla API token, without copying Joomla/JCB business logic into the client.

Implemented

• Standalone joomengine/mcp-client SDK and joomengine-mcp stdio executable.
• Dockerfile/Compose launcher with locked dependencies, non-root/read-only execution, URL/token environment configuration and documented private-CA support.
• Generic server-discovered tools, resources, prompts and job responses; bounded concurrent HTTPS, JSON-RPC IDs, pagination, finite SSE, cancellation, sessions and clean shutdown.
• Private named-site credential storage, path/link/ownership checks, atomic updates and no automatic retry of ambiguous writes.
• Exact stdio byte bounds, including whitespace frames and EOF behavior.

Validation

All final-head checks pass on PHP 8.3 and 8.4:

• Client contracts and actual Docker Compose/TLS checks
• Installed Joomla SDK/executable interoperability

Includes 25 bridge checks, nine Compose/TLS checks per image and 14 live installed assertions per PHP version. The component's full coordinated acceptance additionally verifies generic-client JCB compiler/package/jobs, partial-effect recovery and hash-verified artifact downloads.

See docs/DOCKER.md for the ready-to-use AI launcher configuration. Remote stdio retains the Joomla API user's ACL and cannot acquire local console authority.

Related component and console plugin. No merge, release publication, registry image publication or Packagist registration is performed.