Add pcov extension in dockerfiles and slic pcov command

[defunctl]

Summary

Adds PCOV support to SLIC so projects can generate code coverage faster than Xdebug-backed coverage.

This adds PCOV to both the slic and wordpress containers, keeps it disabled by default, and introduces a new slic pcov command for enabling, disabling, and checking PCOV state.

Changes

• Adds PCOV to the SLIC and WordPress Docker images.
• Adds slic pcov on|off|status with detection of xdebug and ability to disable it.
  Updatesslic xdebug` to also check if pcov is enabled.
• Persists desired PCOV state through PCOV_ENABLED.
• Applies PCOV state immediately to running containers.
• Applies PCOV state on container startup.
• Preserves the upstream WordPress image ENTRYPOINT.
• Adds pcovon and pcovoff helpers inside slic shell.
• Updates README and SLIC skill docs.
• Bumps SLIC to 2.3.0.
• Build the images on release/x.x.x branches in addition to just x.x.x branches that already existed.

Example Usage

slic pcov on
slic run wpunit --coverage --coverage-xml clover.xml --disable-coverage-php
slic pcov off

Example composer.json scripts:

{
  "scripts": {
    "test:coverage": [
      "slic pcov on --yes",
      "slic run wpunit --coverage --coverage-xml clover.xml --disable-coverage-php",
      "slic pcov off"
    ],
    "test:coverage-html": [
      "slic pcov on --yes",
      "slic run wpunit --coverage --coverage-html coverage --disable-coverage-php",
      "slic pcov off"
    ]
  }
}

Notes

PCOV is intended for coverage generation only. Xdebug remains available for debugging through the existing slic xdebug command.

The WordPress image keeps the upstream docker-entrypoint.sh flow intact. PCOV state is applied through the apache2-foreground command path so WordPress initialization behavior remains owned by the base image.

Verification

• php -l slic.php
• php -l src/slic.php
• php -l src/commands/pcov.php
• git diff --check
• Built SLIC PHP 7.4 image
• Built WordPress PHP 7.4 image
• Verified PCOV on/off behavior
• Verified PCOV_ENABLED=1 is honored at container startup