[b-re-w]

Allow explicit text field typography and icon button layout control.

Closes #507

[b-re-w]

macOS Visual Capture Verification (FR-75, #507)

Visual evidence captured off-screen via Skia / Desktop Compose UI test on macOS arm64.

1. Visual Identity Verification (No tokens set)

Comparison between before (develop at 19b63e3f, prior to #511/#512) and after (develop at a2754f1e):

• 511_default_before.png vs 511_default_after.png: 0 pixel difference (identical SHA-256 hash).
• Default toolkit typography, default height (minHeight = 40dp), default internal padding, and default icon button sizing are strictly preserved when no custom tokens are specified.

State	File	SHA-256
Before (19b63e3f)	511_default_before.png	33a18c7e03619798ad08c7ae4f5fc65a30805fc81c4207488a27e8c49ebd2355
After (a2754f1e)	511_default_after.png	33a18c7e03619798ad08c7ae4f5fc65a30805fc81c4207488a27e8c49ebd2355

2. Custom Tokens in Effect (a2754f1e)

Verification of the new tokens taking effect over defaults:

• TextField typography: font_size(15.0), font_weight(600), line_height(22.0), letter_spacing(0.5), color(Paint::Literal(0xFF0066CC)) applied directly to the text rendering.
• TextField geometry: explicit height(36.0) and padding_each(12.0, 6.0, 12.0, 6.0) override toolkit default height and internal padding.
• Icon Button layout: wordless button (Button("") with IconRole::Add) with explicit size(32.0, 32.0) and corner_each(8.0, 8.0, 8.0, 8.0) bypasses button minimum height and horizontal text padding, rendering as a compact 32x32 icon button.

Comparison	Image
Default vs Custom (FR-75)
Before vs After Identity

Artefact Hashes

• 511_comparison_side_by_side.png (SHA-256: fa7e717222236dad396ebc5c8787f339e1ec2788e7b45549f703590ee4b30c43)
• 511_default_before_vs_after.png (SHA-256: 959a8db6813547673479c60e2b8a6495df262405eaafa6402b9a3c387ae0f11d)
• 511_custom_after.png (SHA-256: eb6538fa1507b8fc01d9812e5a7cb1d8a0361b19e9874632af5dfd7474677aa2)
• 511_default_after.png (SHA-256: 33a18c7e03619798ad08c7ae4f5fc65a30805fc81c4207488a27e8c49ebd2355)
• 511_default_before.png (SHA-256: 33a18c7e03619798ad08c7ae4f5fc65a30805fc81c4207488a27e8c49ebd2355)