Let a duplicated node's pins reset to the original's default [patch]

[matt-edmondson]

Fixes #476

What was wrong

NodeEditorEngine.DuplicateNodes gave each copied pin a new id and wrote the original's current value to it, but never seeded a default for it in PinValueStore. PinValueStore.Reset only works on a pin that has a seeded default, so ResetPinValue returned false and did nothing on every pin of a duplicated node. Copies of factory-bound nodes had the same problem, and undo/redo kept it because CaptureNode recorded HasDefault = false.

Change

• Before a copied pin's value is written, the original's seeded default (from pinValues.TryGetDefault) is seeded onto the copy.
• Seeding also sets the value. If the original holds null over a non-null default, the copy's value is put back to null so the seed doesn't replace it.
• The DuplicateNodes remarks now say that a copied pin resets to the original's default.

Tests

• DuplicateNode_CopiedPinResetsToTheOriginalsDefault is the issue's repro on a spec-created node. The copy arrives with 42, the reset returns true and gives 5, and the original is unchanged.
• DuplicateNode_CarriesANullValueOverANonNullDefault: a null on the original is still null on the copy, and a reset gives the default back.
• ResetPinValue_OnACopyOfABoundNode_PutsTheOriginalsDefaultBack covers a factory-bound TunableNode: the copy resets to 128 and the original's instance keeps 200.

With the NodeEditorEngine.cs change reverted, all three new tests fail on the ResetPinValue assertion. With the change in place, all 269 tests in ImGui.NodeEditor.Tests pass on net10.0.

🤖 Generated with Claude Code

https://claude.ai/code/session_018AK9FUHZoZnfAL1aQuEtAR

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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