fix: skip dashboard deploy when scan artifacts expired

[mananjain99]

Prevents overwriting real vulnerability data with zeros when scan artifacts have expired. If no trivy/snyk results found, the workflow exits early and preserves existing dashboard data.

[snykgituser]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues
✅	Licenses	0	0	0	0	0 issues
✅	Code Security	0	0	0	0	0 issues

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