Phase 2: Add performance benchmarks to CI

[RAprogramm]

Task

Run criterion benchmarks in CI and track performance trends with regression detection.

Implementation

1. Add benchmark job to workflow
2. Run cargo bench --no-fail-fast --all-features
3. Store benchmark results as artifacts
4. Compare with baseline from previous runs
5. Alert on >10% performance regression

Benefits

• Automatic detection of performance regressions
• Historical performance tracking
• Prevents accidental slowdowns in production

Acceptance Criteria

• Benchmarks run in CI
• Results stored as artifacts
• Baseline comparison implemented
• Alert on >10% regression

Parent: #175