feat: add Logger::init() call to monitoring server startup paths

[mvillmow]

Summary

Initializes the logger explicitly in both HealthCheckServer::start() and PrometheusExporter::start() methods to ensure spdlog is ready before the first log message is emitted.

This implements explicit startup initialization rather than relying on the lazy initialization guard in Logger::log(), providing a clearer and more explicit initialization contract.

Changes

• Added Logger::init() call to HealthCheckServer::start() immediately after the running flag check
• Added Logger::init() call to PrometheusExporter::start() immediately after the running flag check
• Both calls are idempotent (Logger::init() checks for existing logger before creating a new one)

Testing

• Format check passed
• No compilation changes required (Logger::init() is already available and idempotent)

Closes #336

[github-actions]

✅ Dependency Audit

Severity	Count
Critical	0
High	0
Medium	0
Low	0

See the Security tab for detailed findings.

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Workflow: Dependency Audit

[github-actions]

Security Scan Results

• ❌ Secret Scanning: Potential secrets found
• ✅ SAST: Completed (check Security tab for details)
• ✅ Dependency Scanning: Completed
• ✅ C++ Static Analysis: Completed
• ✅ Docker Image Scanning: 0 high, 22 medium vulnerabilities (acceptable)

Recommendations

• Review findings in the GitHub Security tab
• Check artifact uploads for detailed reports
• Address critical Docker vulnerabilities immediately

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Workflow: Security Scanning