Prevent inspector float edits from collapsing/rounding literal values

[Copilot]

Editing AstFieldKind.Fraction fields in the inspector was using a fixed-format double display path that could truncate precision and collapse small magnitudes (e.g. 1e-9) toward 0 on commit. This change makes the inspector’s double formatting round-trip-safe for source literals and locks behavior with a focused regression test.

• Inspector numeric format (behavior fix)

  • AstGraphEditor now configures its property grid with a round-trip-oriented double format (%.17g) so displayed/parsed values preserve literal magnitude and precision across edits.
  • This addresses both tiny scientific-notation values and high-precision literals touched in the UI.

• Regression coverage (UI inspector path)

  • Added an inspector panel test for LiteralExpression<double> with a small magnitude (1e-9) that verifies:
    • value remains unchanged after draw/selection (no silent mutation),
    • value is preserved through an edit commit round-trip.

private static readonly ImGuiWidgets.PropertyGridOptions InspectorGridOptions = new()
{
	LabelColumnWeight = 0.95f,
	DoubleFormat = "%.17g",
};

• Fixes Editing a floating-point literal in the inspector truncates it to six decimal places #43

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

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