Add host-path alias symlink startup hook and validation coverage

[UltraBob]

Summary

Implements host-path alias parity via a startup symlink strategy instead of a bind-mount alias.

What changed

• Added .ddev/web-entrypoint.d/90-dcq-host-path-alias.sh.
• Hook now creates a host-path alias symlink to /var/www/html at container startup.
• Added opt-out via DCQ_HOST_PATH_ALIAS=0|false|off.
• Added cleanup behavior for add-on-managed aliases when disabled.
• Wired new entrypoint hook into install.yaml project_files and removal_actions.
• Documented behavior and env var in README.md.
• Added bats coverage for:
  • existing path-map behavior,
  • alias creation behavior,
  • alias-disable behavior.

Important fix included

Entry-point scripts are sourced by DDEV. The initial implementation used exit, which could terminate container startup when aliasing was disabled. This PR fixes that by using safe sourced-script return behavior.

Validation

Targeted bats checks pass:

• path map prefers DDEV_HOST_PROJECT_ROOT
• host-path alias symlink is created on restart
• host-path alias can be disabled via DCQ_HOST_PATH_ALIAS

Notes

This PR establishes the alias architecture and keeps existing path-mapping wrappers in place for safety.
A follow-up phase will investigate removing/simplifying wrapper path-mapping logic to rely on host-path parity directly.

Refs #19

[UltraBob]

Follow-up implementation for TASK-0052 simplification scope is now pushed to feature/host-path-alias-parity (commit 76007df).

What changed:

• Added shared helper behavior in commands/helpers/path-map.sh:
  • trim quoted compose approot, normalize host-root slash handling,
  • prefer host-path alias pass-through when available,
  • new map_to_project_relative() helper.
• Refactored wrappers to use shared normalization helper instead of repeated inline /var/www/html stripping:
  • cspell, cspell-suggest, eslint, eslint-fix, stylelint, stylelint-fix, prettier, prettier-fix.
• Simplified PHPStan JSON host-path rewrite setup to use helper-resolved HOST_ROOT fallback.
• Added tests:
  • path map keeps host absolute paths when alias exists
  • path map falls back to container path when alias is disabled

Validation run A (5 tests):
bats ./tests/test.bats --filter "path map prefers DDEV_HOST_PROJECT_ROOT|path map keeps host absolute paths when alias exists|path map falls back to container path when alias is disabled|host-path alias symlink is created on restart|host-path alias can be disabled via DCQ_HOST_PATH_ALIAS" --print-output-on-failure

Validation run B (6 tests):
bats ./tests/test.bats --filter "stylelint-fix rewrites explicit web paths with non-web docroot|eslint fixed mode falls back to .eslintrc.json when passing config is missing|stylelint-fix fails with helpful message when project config is missing|stylelint-fix uses nearest config when root config is missing|prettier-fix fails with helpful message when project config is missing|phpstan fails with helpful message when project config is missing" --print-output-on-failure

Both runs passed.

[UltraBob]

Implemented the TASK-0052 follow-up pass to enforce host-path alias parity and remove fallback host->container path rewrites.

What changed in this push (e2af138):

• Enforced alias setup in web-entrypoint.d/90-dcq-host-path-alias.sh.
  • Removed DCQ_HOST_PATH_ALIAS opt-out behavior.
  • Alias conflicts on existing non-directory paths now fail with an explicit error.
  • Existing directories are treated as valid parity paths.
• Simplified commands/helpers/path-map.sh:
  • map_path() now keeps host paths host-native (no /var/www/html fallback remap).
  • Retained centralized normalization context + map_to_project_relative().
• Removed wrapper rewrite loops where alias parity now makes them unnecessary:
  • commands/web/phpcs
  • commands/web/phpcbf
  • commands/web/phpstan (kept output-side canonical->host rewrite behavior)
  • cleaned remaining config arg mapping in cspell, cspell-suggest, prettier.
• Updated docs:
  • alias now documented as enforced, with restart note after install/upgrade.
  • removed DCQ_HOST_PATH_ALIAS user toggle guidance.
• Updated tests:
  • replaced disabled-alias fallback test with enforced-alias semantics.
  • added passthrough checks for phpcs/phpcbf host-absolute --stdin-path and --standard args.

Validation rerun after disk cleanup:

• bats ./tests/test.bats --print-output-on-failure
• Result: 35/35 passing (expected skips for DCQ_FULL_TESTS-gated tests).