ci: Add GitHub Actions security linting with zizmor

[nbrieussel]

Contexte

This PR adds security-focused linting for GitHub Actions workflows to detect vulnerabilities, secrets, and dangerous patterns before they reach production.

Changements

• Dependency: Added zizmor 0.5 to mise.toml
• Workflow: Added zizmor job to existing lint-workflows workflow
  • Detects hardcoded secrets
  • Identifies excessive permissions
  • Flags dangerous expression injections
  • Reports security anti-patterns
• Pre-push Hook: Updated to run both actionlint (syntax) and zizmor (security)

Bénéfices

• Early detection of security vulnerabilities in workflows
• Prevents accidental secret leaks
• Enforces principle of least privilege for permissions
• Complements GitHub's Push Protection

Tests

• Run locally: zizmor .github/workflows/*.yml
• Both actionlint and zizmor must pass pre-push
• Check that both checks appear in GitHub Actions on PR

[github-advanced-security]

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