ci: add gitleaks on pre-commit phase

[ericodx]

Summary

• Add gitleaks to .pre-commit-config.yaml to detect hardcoded secrets and credentials before they reach the repository
• Update sonar-project.properties with revised SonarCloud configuration

Type of Change

• ci: Changes related to continuous integration and deployment scripts.
• chore: Other changes that do not fit into the previous categories.

Invariants Checklist

• Detection is deterministic (same input → same output)
• Source files are never modified (tool is read-only)
• Source locations are accurate (file, line, column)
• No false negatives introduced (previously detected clones are still detected)
• Performance not degraded for large codebases
• Swift 6 Strict Concurrency compatible
• Pipeline stages remain stateless pure transformations

Pipeline Impact

• None

Testing

• All tests pass locally (swift test)