ci: enable incremental dependency-check updates

[FrankChen021]

Description

• stop purging the OWASP Dependency-Check database before every scan
• restore and save the database through a dedicated GitHub Actions cache
• use a stable data directory and a 24-hour NVD freshness window
• add a manual workflow trigger for validation

Testing

• git diff --check
• YAML parse validation
• Dependency-Check 12.2.0 parameter validation
• Cron Job ITs workflow run to be triggered after PR creation

The first run is expected to initialize the cache; a subsequent run will verify that the cached database is restored and only incremental NVD updates are downloaded.

[FrankChen021]

Dependency-Check cache validation for commit 32629a3:

• Initial PR run 32743390989: the cache was initially absent, Dependency-Check downloaded the full NVD set (382,070 records), and the workflow saved the cache with key dependency-check-data-Linux-odc-12.2.2-32743390989.
• Follow-up run 32756643364: the restore step reported "Cache not found" for the odc-12.2.2 keys, so it downloaded the full NVD set again (382,161 records). It later logged "Skipping the NVD API Update as it was completed within the last 240 minutes."

Conclusion: this follow-up did not demonstrate an Actions cache hit or incremental NVD update. The version-scoped key is present, but the cache saved by the pull_request run was not visible to this workflow_dispatch run, likely because of GitHub Actions cache scope by event/ref. Both runs failed on CVSS >= 7 findings after the scan; neither showed the previous URL-length database-schema error.