chore: setup pre-commit, CI secret scanning, and initial lint fixes

[moghit-eou]

Add gitleaks pre-commit hook and CI workflow

• Adds gitleaks to .pre-commit-config.yaml to catch hardcoded secrets locally before commit.
• Adds a CI workflow that runs gitleaks on pull requests and uploads findings as SARIF to GitHub code scanning.
• Lints existing files (whitespace, formatting cleanup) to bring them in line with the new pre-commit hooks.

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

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For more information about GitHub Code Scanning, check out the documentation.