text_edit: scale the single-line horizontal padding with the field height

The previous commit put the password eye, the caret and the whole multiline layout in physical pixels, but the single-line variant still inset its text by the raw `theme::PAD_H`: 20 physical px whatever the scale. On a scale-2 panel a field 88 px tall, drawn as a pill of radius 44, kept a 20 px inset, so the first glyph sat inside the rounded end while everything else in the field had grown.
The padding now follows the field height, like the eye already did: `metrics::single_line_pad_h( rect )` is `PAD_H × rect.height / theme::HEIGHT`, built on `single_line_scale`, which replaces the private `password_toggle_scale` of `draw.rs`. The height is the right reference rather than `canvas.geom_px( PAD_H )`: the inset exists to clear the pill's rounded end, whose radius is half the height. With the default height the two agree, since that height is itself `geom_px( HEIGHT )`; when the app pins the height the padding follows that choice instead of the fluid mode, which on a large surface would push it to 1.5 times the design value next to a field the app deliberately kept smaller. It also needs no canvas, so `password_toggle_hit_zone( rect )` keeps its signature.
`draw` resolves the padding once and uses it for the narrowed text rect, the inner clip, the selection band, the placeholder, the text and the caret; `password_toggle_hit_zone` uses it for the half padding beside the eye. `single_line_scroll_x`, `single_line_align_offset` and the single-line branch of `byte_offset_at` use the same helper, so a click still maps to the glyph that was drawn. `hit_test.rs` no longer references `theme` and drops the import. A field `HEIGHT` tall at scale 1 keeps exactly the previous geometry.

src/widget/text_edit/draw.rs

@@ -6,7 +6,7 @@ use crate::types::Rect;
 
 use super::TextEdit;
 use super::hit_test::{ single_line_align_offset, single_line_scroll_x };
-use super::metrics::MultilineMetrics;
+use super::metrics::{ single_line_pad_h, single_line_scale, MultilineMetrics };
 use super::theme;
 use super::wrapping::compute_visual_lines;
 
@@ -47,15 +47,9 @@ fn rect_intersect( a: Rect, b: Rect ) -> Option<Rect>
 	}
 }
 
-// The toggle follows the field height, which is already in physical pixels.
-fn password_toggle_scale( rect: Rect ) -> f32
-{
-	rect.height / theme::HEIGHT
-}
-
 fn password_toggle_reserve( rect: Rect ) -> f32
 {
-	( theme::PASSWORD_TOGGLE_SIZE + theme::PASSWORD_TOGGLE_SLOP * 2.0 ) * password_toggle_scale( rect )
+	( theme::PASSWORD_TOGGLE_SIZE + theme::PASSWORD_TOGGLE_SLOP * 2.0 ) * single_line_scale( rect )
 }
 
 /// Hit rect for the eye icon at the right edge of a `TextEdit`
@@ -67,7 +61,7 @@ fn password_toggle_reserve( rect: Rect ) -> f32
 pub fn password_toggle_hit_zone( rect: Rect ) -> Rect
 {
 	let zone_w = ( password_toggle_reserve( rect )
-		+ theme::PAD_H * 0.5 * password_toggle_scale( rect ) ).min( rect.width );
+		+ single_line_pad_h( rect ) * 0.5 ).min( rect.width );
 	Rect
 	{
 		x:      rect.x + rect.width - zone_w,
@@ -127,9 +121,10 @@ impl<Msg: Clone> TextEdit<Msg>
 		{
 			0.0
 		};
+		let pad_h     = single_line_pad_h( rect );
 		let text_rect = Rect
 		{
-			width: ( rect.width - toggle_reserve ).max( theme::PAD_H * 2.0 ),
+			width: ( rect.width - toggle_reserve ).max( pad_h * 2.0 ),
 			..rect
 		};
 		let scroll_x  = single_line_scroll_x( canvas, text_rect, &self.value, cursor_pos, secure, font_size );
@@ -143,9 +138,9 @@ impl<Msg: Clone> TextEdit<Msg>
 		let outer_clip = canvas.clip_bounds();
 		let inner_rect = Rect
 		{
-			x:      rect.x + theme::PAD_H * 0.5,
+			x:      rect.x + pad_h * 0.5,
 			y:      rect.y,
-			width:  ( rect.width - theme::PAD_H - toggle_reserve ).max( 0.0 ),
+			width:  ( rect.width - pad_h - toggle_reserve ).max( 0.0 ),
 			height: rect.height,
 		};
 		canvas.set_clip_rects( &interior_clip( &outer_clip, inner_rect ) );
@@ -170,7 +165,7 @@ impl<Msg: Clone> TextEdit<Msg>
 			} else {
 				self.value[s..e].to_string()
 			};
-			let x0 = rect.x + theme::PAD_H + align_x - scroll_x
+			let x0 = rect.x + pad_h + align_x - scroll_x
 				+ canvas.measure_text( &prefix_text, font_size );
 			let w  = canvas.measure_text( &span_text, font_size );
 			let sel_rect = Rect
@@ -191,7 +186,7 @@ impl<Msg: Clone> TextEdit<Msg>
 			);
 			canvas.draw_text(
 				&self.placeholder,
-				rect.x + theme::PAD_H + placeholder_align_x,
+				rect.x + pad_h + placeholder_align_x,
 				text_y,
 				font_size,
 				theme::placeholder(),
@@ -199,7 +194,7 @@ impl<Msg: Clone> TextEdit<Msg>
 		} else {
 			canvas.draw_text(
 				&text,
-				rect.x + theme::PAD_H + align_x - scroll_x,
+				rect.x + pad_h + align_x - scroll_x,
 				text_y,
 				font_size,
 				theme::text(),
@@ -215,7 +210,7 @@ impl<Msg: Clone> TextEdit<Msg>
 			} else {
 				self.value[..safe_cursor].to_string()
 			};
-			let cursor_x = rect.x + theme::PAD_H + align_x - scroll_x
+			let cursor_x = rect.x + pad_h + align_x - scroll_x
 				+ canvas.measure_text( &cursor_text, font_size );
 			// Caret height follows the text line, not the field box — a
 			// tall field (launcher pill) otherwise grows a caret twice
@@ -249,7 +244,7 @@ impl<Msg: Clone> TextEdit<Msg>
 		if let Some( ( visible, _ ) ) = self.password_toggle.as_ref()
 		{
 			let icon_name = if *visible { "actions/invisible" } else { "actions/visible" };
-			let icon_px   = ( theme::PASSWORD_TOGGLE_SIZE * password_toggle_scale( rect ) ).round().max( 1.0 ) as u32;
+			let icon_px   = ( theme::PASSWORD_TOGGLE_SIZE * single_line_scale( rect ) ).round().max( 1.0 ) as u32;
 			if let Some( ( rgba, iw, ih ) ) = crate::theme::icon_rgba( icon_name, icon_px )
 			{
 				let tinted = crate::theme::tint_symbolic( &rgba, theme::placeholder() );