fix: stop pr_checks alias forwarding empty inputs as overrides

[clouddrove-ci]

The compat alias pr_checks.yml declares its inputs without defaults, then forwards all of them to pr-checks.yml. An input the caller leaves unset is forwarded as an empty string, which overrides the downstream default instead of falling back to it.

The visible symptom is PR title validation. pr-checks.yml builds:

FULL_REGEX="^(${TYPES})(\([a-zA-Z0-9_-]+\))?:\s+${{ inputs.subjectPattern }}$"

With subjectPattern forwarded as "" the regex becomes:

^(fix|feat|...)(\([a-zA-Z0-9_-]+\))?:\s+$

which requires the title to end immediately after type: . No valid Conventional Commit title can pass. Callers see PR title does not follow Conventional Commit format on titles that are correct.

checkLabels has the same problem in the other direction: a caller that omits it gets false forwarded, silently disabling the label check that is documented to default to true.

Fix: give the alias the same defaults as pr-checks.yml, so a caller that omits an input forwards the real default. Also forwards commitlintConfig, which the alias accepted nowhere and never passed through.

Verified all six inputs now match the target's defaults exactly.

Observed on clouddrove/terraform-aws-sqs, where PRs #30, #31 and #33 all failed title validation with valid titles. Worked around there by calling pr-checks.yml@v2 directly; terraform-aws-sns is still on the alias and affected.