Honor ignore files and exclude tests from scans

[aksOps]

Summary

• Parse .gitignore, .ignore, and .git/info/exclude during scans.
• Add opt-in --exclude-tests support for scan and diff.
• Add default test-file patterns for Java, Python, TypeScript/JavaScript, Go, and Rust.

Verification

• go test ./... -count=1
• go vet ./...
• go build -trimpath -o /tmp/scanner ./cmd/scanner
• staticcheck ./...
• gosec -quiet -exclude=G204,G304,G401,G505 ./...
• sonar predictor: no MAJOR+ issues
• CLI scenario verified --exclude-tests drops test warnings and counts skipped files

Tag pushed: 0.0.1-1

Note: direct push to main was rejected by branch protection, so this follows the protected-branch PR path.

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
87.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud