Simplify releases and separate webservices plugin ownership

[Llewellynvdm]

The component repository was carrying release plumbing and an embedded webservices plugin that belong to the shared tools and a separate extension repository.

This PR uses the native Octoleo actions directly, with one git-user setup. It removes temporary action checkouts, config rendering, duplicate hash/push handling and the embedded webservices installer lifecycle.

• .octojpack is complete and usable independently: fixed source repositories, joomengine/mcp_package/main destination, and raw GitHub URLs for the licence, package update feed and shared changelog.
• The populated update feed stays in this repository and identifies pkg_joomengine_mcp with Joomla's package client ID 0. It downloads versioned ZIPs from mcp_package.
• The manual release workflow freezes the pending changelog version and tags the component, calls OctoJPack, updates the feed from the published package version, then calls OctoShoom. Package publication must precede hashing because the feed downloads that package archive.
• Webservices routing moves to mcp_webservices PR #1. OctoJPack includes component, console and webservices as three independent extensions. The component installer neither copies nor removes plugins.
• Source ZIP installation and committed runtime dependencies remain supported. Agent and release documentation record these ownership and changelog conventions.

Validation on the current component revision 29deb6dfeaa84c238e13ba4a3463a355d5f8e92c:

• PHP contracts: PHP 8.3/8.4 pass.
• Installed Joomla: all four PHP 8.3/8.4 × MySQL/PostgreSQL combinations pass, including independent webservices lifecycle checks.
• JCB golden-image integration: passes.
• Webservices source checks: pass for the exact plugin revision tested here, 7853f864d70ff8aea43c488bc3a93bd6e5724623.
• Local validation: 22 release assertions, 34 source-installability assertions, 34 runtime assertions, 11 ownership assertions, PHP/Bash syntax, workflow lint and whitespace checks.

Merge the webservices extraction before this PR. Its reviewed plugin tag and the console plugin tag must exist before running the component release. The initial 0.1.1 feed entry is prepared metadata; this PR does not publish a release or claim an existing package download/checksum.

Related console workflow simplification: mcp_plugin PR #2.