[mmohankrishna-lab]

_RenderDecoration.computeMinIntrinsicHeight computed the minimum container height differently from _layout:

	Condition	Floor
_layout	isDense || isCollapsed || expands	inputHeight
computeMinIntrinsicHeight (before)	isDense || expands	0.0

This caused two mismatches between the intrinsic height and the laid out height:

1. isDense: true with compact visual density (the default on desktop and web): the density offset (-8) shrinks the content height below the input height. Layout clamps it back up to inputHeight, but the intrinsic path clamped to 0.0, so the intrinsic height was 8px too short. Inside IntrinsicHeight, this produced the A RenderFlex overflowed by 8.0 pixels error reported in the issue.
2. isCollapsed: true without isDense (including InputDecoration.collapsed): the intrinsic path still applied the kMinInteractiveDimension (48px) floor, while layout used inputHeight, so the intrinsic height was too tall.

This PR aligns computeMinIntrinsicHeight with _layout.

Density	Decoration	Laid out height	Intrinsic before	Intrinsic after
compact	isDense + isCollapsed, zero padding	24	16	24
compact	isDense, zero padding	24	16	24
standard / compact	isCollapsed	24	48	24
standard / compact	InputDecoration.collapsed	24	48	24

Fixes flutter/flutter#190536

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[gemini-code-assist]

Code Review

This pull request updates the minimum intrinsic height calculation in InputDecorator to match its laid out height when isDense or isCollapsed is true, and adds corresponding regression tests. The review feedback recommends replacing the null-assertion operator on decoration.isDense! with decoration.isDense == true to avoid potential runtime exceptions.

[Piinks]

This LGTM, thank you!