feat: add WooCommerce APort guardrail plugin

[nexicturbo]

Summary

• add a WooCommerce plugin example under examples/ecommerce/woocommerce
• verify checkout orders and refunds with configurable APort policy ids
• add a settings page, authenticated refund preflight endpoint, order-note audit trail, and docs
• include PHPUnit coverage for agent-id extraction and verification context builders

Verification

• git diff --check
• LC_ALL=C rg -n "[^\\x00-\\x7F]" examples/ecommerce/woocommerce || true

PHP tooling note: this environment does not have php, composer, Docker, or Podman installed, so I could not run php -l or PHPUnit locally. The plugin includes composer test and composer lint scripts for reviewer-side validation.

/claim #8

Closes #8

[nexicturbo]

Quick review note for maintainers: this PR is scoped to issue #8 and adds the WooCommerce example under examples/ecommerce/woocommerce with:

• order/refund verification guardrails for WooCommerce hooks
• APort client settings, timeout/error handling, and deny-by-default behavior when verification fails
• README setup notes plus audit/logging behavior
• PHPUnit context tests and Composer scripts for reviewer-side validation

Local validation available in this environment: git diff --check and an ASCII scan of the new example files passed. PHP/Composer are not installed locally here, so the PR body calls out the reviewer-side composer test / composer lint commands instead of pretending I ran them.