Add comprehensive no_std matrix testing

[RAprogramm]

Problem

Current CI only tests:

• --no-default-features (basic no_std)
• --all-features (full std)

Missing: Feature combination testing

Professional Solution

Add matrix testing for all critical no_std + feature combinations:

no-std:
  strategy:
    matrix:
      features:
        - no-default-features
        - no-default-features --features tracing
        - no-default-features --features metrics  
        - no-default-features --features colored
        - all-features

Benefits

• 🛡️ Prevents regressions like no_std compilation broken in v0.25.0 #326
• ✅ Tests all feature combinations
• 🚀 Parallel execution (~same time)
• 📊 100% confidence in no_std support

Implementation

Will implement in v0.25.1