Add focused WordPress integration package

[chubes4]

Summary

• add wp-coding-agents-integration as the canonical regular plugin for retained WordPress runtime adapters
• keep host probes private to the provider and expose them through Intelligence-owned, fail-closed filters
• derive carried-plugin installation and removal from explicit profile intent, with fail-closed single-site and multisite cleanup
• record the representative DMC census and retirement of the unused PR-review flows

Intelligence and Data Machine do not reference this package or its PHP namespace.

Verification

• bash tests/carried-claude-code-plugin.sh
• bash tests/integration-adapters.sh
• bash tests/installation-profile.sh
• bash tests/source-reconcile.sh
• bash tests/dmc-migration-inventory.sh
• php -d zend.assertions=1 -d assert.exception=1 tests/wordpress-integration-package.php
• shellcheck lib/carried-plugins.sh lib/desired-state-reconciler.sh lib/integration-adapters.sh
• independent final code review found no remaining production defects

Closes #530.

AI Assistance

OpenAI GPT-5.6 Sol via OpenCode performed the installed-state census, implemented the focused provider and hook adapters, added verification coverage, and reviewed the final diff under Chris Huber's direction.