[Feature]: Introduce FFTS into p2p transport

[pyxyzc]

🚀 The feature, motivation and pitch

Goal

Introduce FFTS into p2p transport with a clear three-layer split:

• FftsDispatcher: base FFTS task builder and launcher
• FftsEngine: per-device FFTS execution capability built on top of FftsDispatcher
• FftsTransport: multi-device transport built on top of FftsEngine

Map

• PR 1: add FFTS dispatcher base capability
• PR 2: add per-device FFTS engine
• PR 3: add multi-device FFTS transport

Note: PR1 code is based on the FFTS usage path mentioned in #990 and introduced in #1039 on develop, and will be marked as co-authored by NaganooMei.

Design Notes

Validation

• Unit tests for FftsDispatcher
• Unit tests for per-device FftsEngine
• Unit tests for multi-device FftsTransport
• Run H2D / D2H smoke test on real device Ascend A3

Alternatives

No response

Additional context

No response

[pyxyzc]

@mag1c-h @Wwwzff @nrj868 @Infinite666 @ygwpz

[pyxyzc]

@ayaka836