Create performance benchmark suite

[pgatzka]

User Story

As a maintainer, I want performance benchmarks so that I can detect performance regressions.

Description

Create JMH benchmarks for:

Metrics to benchmark:

• Request execution time (p50, p95, p99)
• Code generation speed
• Memory usage per request
• Throughput (requests/second)

Implementation:

• JMH benchmark module
• Baseline metrics documented
• CI integration for regression detection

Acceptance Criteria

• JMH benchmark suite created
• Baseline metrics documented
• CI integration for regression detection
• Benchmark results published in PR comments
• Implemented code is covered with automated tests
• Documentation has been updated