[WIP] Fix code based on review comments

[Copilot]

• Fix fingerprint fallback logic in server/src/lib/sarif-utils.ts — apply the reviewer's suggestion to only fall back to full-path when fingerprints are absent, not when both results have fingerprints that don't match (keeps fingerprint mode strict)
• Add unit test for "fingerprints present but mismatch, locations overlap" case in server/test/src/lib/sarif-utils.test.ts
• Rebuild server dist bundle
• Run tests to verify all changes pass