Use TypeAlias and consistent naming for sbi types

[janfb]

In PR #1633, I noticed that the typing module defines NewType instead of using TypeAlias. For our purposes, an alias is just fine and comes without consequences for documentation rendering and type checking (NewType does not implicitly perform type checking according to the actual underlying type). Therefore:

• Replace NewType with TypeAlias for SummaryWriter, Distribution, Tensor, Transform.
• Rename TensorboardSummaryWriter → TensorBoardSummaryWriter.
• Remove unused TorchModule alias; use torch.nn.Module where needed (e.g., NPE_A.build_posterior).
• Update imports/annotations across trainers to new alias.

Notes:

• Type-only refactor; no behavior changes.
• Breaking rename: external imports of TensorboardSummaryWriter/TorchModule must update.

[codecov]

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Additional details and impacted files

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Flag	Coverage Δ
unittests	82.55% <100.00%> (?)

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Files with missing lines	Coverage Δ
sbi/inference/trainers/nle/mnle.py	95.45% <100.00%> (ø)
sbi/inference/trainers/nle/nle_a.py	100.00% <100.00%> (ø)
sbi/inference/trainers/npe/mnpe.py	95.45% <100.00%> (ø)
sbi/inference/trainers/npe/npe_a.py	63.91% <100.00%> (ø)
sbi/inference/trainers/npe/npe_b.py	100.00% <100.00%> (ø)
sbi/inference/trainers/npe/npe_c.py	73.33% <100.00%> (ø)
sbi/inference/trainers/nre/bnre.py	44.82% <100.00%> (ø)
sbi/inference/trainers/nre/nre_a.py	100.00% <100.00%> (ø)
sbi/inference/trainers/nre/nre_b.py	100.00% <100.00%> (ø)
sbi/inference/trainers/nre/nre_c.py	100.00% <100.00%> (ø)
... and 1 more

[manuelgloeckler]

Looks good.

Regarding typing for PyTorch > 2.6 (by now we are already at 2.8). So I dont think this will get fixed in a while (and it might be best to ignore the errors and allow the newer versions). I think the underlying reason is that the updated new version does not come with updated/correct type "stubs" (I some extra files which does give type hints for external non-python function to pyright) . Its just that certain "inplace" operations on Tensors are not recognized anymore by pyright.