v0.3.0 - Reusable AXI4 UVM VIP

Extracts parameterized AXI4 master and reactive-target UVM agents into a standalone VIP package while preserving the measured fabric closure: 30/30 named scenarios, 100/100 seeded-random runs, 8/8 real UVM tests, 130/130 SystemC replays, 56/56 functional bins, 46/46 canonical crosses, and 24/24 advanced crosses. Includes an independent VIP self-test with zero UVM errors, fatals, or mismatches.