feat: add automatic transport routing

[Chand1erLiu]

Summary

• add node-aware automatic transport selection between peer memory and direct URMA
• propagate local-rank topology into UDMA setup and route cross-node peers through UDMA
• integrate transport routing into EP dispatch paths and update EP, memory, and UDMA demos
• add host routing, selector, validation, and source-guard coverage

Test plan

• git diff --cached --check
• Run the EP and UDMA C++ unit tests (not run locally: cmake, g++, and bash are unavailable in this Windows environment)
• Run the cross-host EP, memory, and UDMA demos on Ascend hardware

[Chand1erLiu]

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[Kur0x]

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