Fix nightly operator test failures across nxp_rt600 and DLA_V130 backends

[ethansfng]

Summary:
Fix 6 categories of nightly operator test failures by addressing FACTO test generation constraints and kernel bugs:

FACTO constraint fixes (facto_util.py):

• div.Tensor_mode: Remove int64 from dtype constraints — nxp_rt600 lacks native int64 support, causing off-by-1 rounding errors via _to_copy fallback
• permute_copy.default: Restrict dtypes to float32/int32 — int8/uint8 cause ISS crashes since xa_nn_transpose doesn't handle sub-word integer types
• pow.Tensor_Scalar: Add Value.Ge(0) constraint — negative inputs produce NaN via negative^fractional, which DSP backends don't implement per IEEE 754

Kernel bug fixes (op_add.cpp, op_sub.cpp):

• Fix || vs && logic error in broadcast type dispatch that caused int32 data to be reinterpreted as float32, producing garbage output on DLA_V130
• Add missing broadcast dispatch cases for Int+Int, Long+Long, Int+Long, Long+Int
• Change static_cast to static_cast to avoid precision loss for large int32 values

HiFi kernel guard fixes:

• op_where.cpp: Disable optimized nnlib path when condition tensor needs broadcasting — xa_nn_elm_select_broadcast_4D only computes strides for inp1/inp2, not the condition tensor
• op_permute_copy.cpp: Disable xa_nn_transpose_32_32 for Float — the nnlib function crashes the ISS for certain tensor shapes; fall back to correct generic implementation
• op_softmax.cpp: Disable optimized nnlib path when softmax dim is not the last dimension — the permuted path allocates temp memory exceeding the budget on resource-constrained targets

Differential Revision: D100873709

[pytorch-bot]

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✅ You can merge normally! (3 Unrelated Failures)

As of commit 450cdbf with merge base a489707 ():

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• pull / test-moshi-linux / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

BROKEN TRUNK - The following jobs failed but was present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / unittest / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• pull / unittest-editable / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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