chore: public OSS release 2.5.3

[keshprad]

Source

• Internal source: main at 7730bc1aceac742dfd0429f7bcf4f5e99ea15535
• Sanitized orphan branch: release/oss-2026-08-05 at 032dc5b3b5b833911c3400358ea8342c547b3d0c
• Released version: 2.5.3
• Release notes: docs/release/skillspector-2.5.3.md

Snapshot contents

• Adds the reviewed 2.5.3 release notes and changelog/version metadata.
• Preserves the reviewed HTTPS-only remote-input hardening and its unit coverage.
• Carries the released static-analysis fixes documented in the release notes.
• Removes no public-only automation or policy files; .github and related public boundaries were inspected and needed no restoration.

Validation

• Internal OSS scrubber: make test-unit passed (1865 passed, 13 skipped, 38 deselected, 4 xfailed).
• Public staged diff: git diff --cached --check passed.
• Internal publication: matching 2.5.3 sdist and wheel checksums verified in Artifactory.

This PR has the required release:publish label for the public release workflow.