ci: split PR title validation into separate workflow

[JoshMock]

Validating PR titles in ci.yml was causing early termination/skipping of some jobs when the PR title is changed. Moving PR title validation to another workflow ensures title validation cannot interfere with other required checks.

[github-actions]

✅MegaLinter analysis: Success

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	2		0	0	0.3s
✅ COPYPASTE	jscpd	yes		no	no	0.43s
✅ REPOSITORY	gitleaks	yes		no	no	42.8s
✅ REPOSITORY	git_diff	yes		no	no	0.06s
✅ REPOSITORY	secretlint	yes		no	no	6.86s
✅ REPOSITORY	trivy	yes		no	no	18.14s
✅ YAML	yamllint	2		0	0	0.71s

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