Avoid loading completed scan results twice

[ianw-oai]

Summary

• Use the completion response instead of loading all findings a second time.
• Load full scan results only when requested.
• Keep the server and setup page on the same updated cache version.

Verification

• Runtime tests: 104 passed; 7 Windows-only tests skipped.
• TypeScript checks passed.
• Changed files pass formatting checks and git diff --check.