[JustSusie]

This adds a NodeData backend for asset types that currently require runtime-generated code, allowing source builds to run under NativeAOT. UnityAssetNodeData=true selects it explicitly, and PublishAot=true selects it automatically through UNITYASSET_NODEDATA.

• Generate concrete interface adapters at compile time, preserving typed edits, nested/array mutations, unknown fields, optional fields, integer signedness, pointer variants and serialized field names.
• Correct per-pair alignment in NodeData maps and annotate reflection-based build-time schema inspection for trimming.
• Add a smoke/benchmark executable, a three-mode comparison script, usage documentation and JIT/NativeAOT CI jobs.

Validation:

• .NET 10 / Windows x64: 565 unit tests passed in each JIT configuration.
• Ordinary JIT, NodeData JIT and Windows NativeAOT smoke tests passed, including TPK loading; final native publish emitted no IL trimming/AOT warnings.
• Regenerated interfaces from the supplied TPK at minimum version 2017.1.0b1 with no differences.
• Ran five-process synthetic benchmarks for each mode; results and commands are in AOT.md. No real asset dataset was available.
• .NET 11 and Linux CI are configured but were not run locally.

The existing untracked AssetModificationTests.cs belongs to an earlier branch and references a removed API. It was preserved, excluded only from local test invocations, and is not included in this PR. Precompiled packages must themselves be built with the fallback setting; application-only symbols cannot change an existing DLL.