refactor(checkpoint): gate direct loads by adapter capability (#3574)

* perf(checkpoint): load aliasing tensors directly

Signed-off-by: Yuhe Zhang <yuhez@nvidia.com>

* perf(checkpoint): expand direct load adapter coverage

Signed-off-by: Yuhe Zhang <yuhez@nvidia.com>

* refactor(checkpoint): clarify write-through load capability

Signed-off-by: Yuhe Zhang <yuhez@nvidia.com>

* docs(skill): place write-through guidance with adapter step

Signed-off-by: Yuhe Zhang <yuhez@nvidia.com>

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Signed-off-by: Yuhe Zhang <yuhez@nvidia.com>