fix[next-dace]: skip failing inout data instead of whole map in local double buffering

[edopao]

Problem

_check_if_map_must_be_handled in local_double_buffering.py bailed on the entire map (return None) whenever a single inout data failed the subset compatibility check (all_inner_subsets[0] == all_inner_subsets[i]). This was inconsistent with the other two checks in the same loop (the "already buffered" check and the "not scalar" check), which correctly did inout_datas.pop(inout_data_name); continue to skip just the failing data.

As a result, in a Map with multiple inout datas, if one data had mismatched read/write subsets, return None suppressed double buffering for all inout datas — including ones that genuinely need it to prevent a write-after-read (WAR) hazard after GT4PyMapBufferElimination inlines the write-back into the Map body.

Fix

Changed return None → inout_datas.pop(inout_data_name); continue in _check_if_map_must_be_handled (local_double_buffering.py:418-419), consistent with the two other checks in the same loop.

This implements the reviewer's (philip-paul-mueller) preferred approach on PR #2815:

"I like the changes and think this is a good addition, but I think that the change is applied at the wrong place. This issue is not new and to solve it gt_create_local_double_buffering() has been created. Since the error surfaced the transformation did not kicked in. Thus I would suggest to patch that one."

Instead of blocking the buffer elimination in simplify.py (PR #2815's approach), the fix lets GT4PyMapBufferElimination(assume_pointwise=True) proceed and relies on gt_create_local_double_buffering to insert a local double buffer that sequences the read before the write.

Test

Added test_local_double_buffering_war_hazard in test_create_local_double_buffering.py:

• Builds a WAR hazard SDFG where a single Map reads G on one branch and writes G (via a tmp buffer) on an independent branch: O(i) = G(i) + 1.0 and G(i) = 2.0 * A(i).
• Applies GT4PyMapBufferElimination(assume_pointwise=True) — asserts it fires (inlines the write-back).
• Applies gt_create_local_double_buffering — asserts it fires (inserts the double buffer).
• Executes the SDFG and verifies O = G_old + 1.0 and G = 2.0 * A (the reader sees the OLD value of G, not the newly written one).

QA

• test_create_local_double_buffering.py: 6 passed (5 existing + 1 new)
• test_map_buffer_elimination.py: 10 passed
• Full transformation_tests/ directory: 334 passed, 3 xfailed
• pre-commit run (ruff, mypy, tach, license): clean
• uv run mypy src/gt4py/next/program_processors/runners/dace/transformations/local_double_buffering.py: no issues
• uv run tach check: all modules validated

[philip-paul-mueller]

Some small comments about the tests, but looks okay.

[edopao]

cscs-ci run default