fix: address transport handshake review feedback

[Spicy-cream]

Summary

Address review feedback on transport handshake feedback.

Changes

• Make upgrade capability checks transport-mode specific.
• Prevent RDMA and UBSHM adapters from being selected for the wrong transport.
• Safely encode short UBSHM shared-memory names.
• Retry interrupted handshake reads and writes.
• Publish handshake phase transitions with release ordering.
• Release RDMA and UBSHM resources when negotiation falls back to TCP.
• Add regression tests for mode-specific dispatch and short UBSHM names.

Validation

• Build: passed.
• Common transport handshake tests: 17/17 passed.
• UBSHM/UBRING tests: 15/15 passed.
• RDMA tests: 86/86 passed.

This PR targets the source branch used by apache#3535.