ci: add path filtering to static-code-analysis workflow

[joshtrichards]

• Resolves: #

Summary

All 5 Psalm jobs in the static-code-analysis workflow currently run unconditionally on every pull request, regardless of which files changed. This means JS-only, docs-only, or other non-PHP changes still trigger 5 full Psalm runs (each doing composer install + full static analysis).

This adds a changes job using dorny/paths-filter (matching the pattern already used by phpunit-*, lint-php, autocheckers, etc.) and gates all Psalm jobs behind it. A summary job is also added to ensure branch protection rules work correctly when jobs are skipped.

No changes to the actual Psalm analysis configuration or behavior -- only when it runs.

Benefit

With 5 jobs running in parallel, the wall-clock time is roughly one job's duration (~20–35 min), and the compute time is 5× that: ~100–175 minutes per workflow run. And less runners occupied.

TODO

• ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI