refactor(tests): convert unsized integer types to explicit-width types

[mvillmow]

Summary

• Replace all bare int, unsigned int, long, etc. with explicit-width types (int32_t, uint32_t, int64_t, size_t) across all 33 test files under tests/
• Covers unit, integration, e2e, load tests, and fixtures
• POSIX-mandated types (int argc, int sock) preserved as-is

Test plan

• All modified files pass just format-check (confirmed: exit 0)
• 33 files changed, 222 insertions(+), 220 deletions(-) — only type name changes, no logic changes

Closes #174

🤖 Generated with Claude Code

[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