[Hotfix 25.9]: [FXC-7096] Disable target_surface_node_count for beta mesher

[mikeparkflex]

Summary

Hot-fix for FXC-7096: the beta surface mesher produces wildly oversized meshes when target_surface_node_count is set on multibody geometries (one customer log: 28 bodies × ~4M tris ≈ 121M tris when the user requested ~500K nodes). The underlying mesher fix is too invasive for the 25.9 RC.

This PR re-narrows the validator gate back to GAI-only for 25.9 (reverting the widening from #1902 / FXC-5958). The field will be re-enabled for the beta mesher in 25.10 once the underlying mesher fix lands.

Backward compatibility

For existing cases that already have target_surface_node_count set with the beta mesher, the validator now auto-strips with a warning rather than rejecting outright:

• use_geometry_AI: allowed (unchanged).
• is_beta_mesher (no GAI): emit add_validation_warning(...) and return None — translator already no-ops on None.
• Legacy mesher: still rejected with ValueError (unchanged).

Test renamed test_beta_mesher_target_surface_node_count_set → test_beta_mesher_target_surface_node_count_stripped and assertions flipped to verify the strip + warning behaviour.

Companion changes

• WebUI gates (React v25_9 codec/panel + Angular legacy getMeshingConfigV259/updateMeshingData): separate flex PR off main.
• compute release-candidate/25.9 Flow360 submodule SHA bump: handled separately.

Test plan

• pytest tests/simulation/translator/test_surface_meshing_translator.py — 25/25 pass, including the renamed _stripped test
• black --check, isort --check, pylint --enable=C0301 clean on the two modified files
• Self-review with /simplify — addressed docstring drift and over-paranoid warnings is not None check
• Manual: load an existing 25.9 case with target_surface_node_count + beta mesher, verify warning surfaces and the value is dropped from the translated JSON

25.10 re-enable

Grep for FXC-7096 to find the temporary branch in ensure_target_surface_node_count_mesher; remove the is_beta_mesher strip-and-warn block and revert the test rename.

🤖 Generated with Claude Code

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Note

Medium Risk
Behavior changes for beta-mesher surface meshing: existing configs with target_surface_node_count will now be silently dropped (with a warning), which can change resulting mesh sizes. Scope is small and isolated to validation/tests, with legacy behavior unchanged.

Overview
Disables target_surface_node_count for the beta surface mesher in 25.9: validation now strips the value and emits a warning unless Geometry AI is enabled, while the legacy mesher continues to raise a ValueError.

Updates the surface meshing translator test to assert the new strip-and-warn behavior and that target_surface_node_count no longer appears in the translated JSON for beta-mesher runs.

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