feat: make spacing input autogrow (webstudio-is#5052)

## Description

When user opens a long value in spacing we now show an input that can
big much bigger, max size 240px for the input. On the other hand it will
be small if value is small AND it will autogrow

<img width="410" alt="image"
src="https://github.com/user-attachments/assets/2ccbdc52-9eea-4f5b-bb44-b4e8d4f7b23f"
/>


## Steps for reproduction

1. click button
2. expect xyz

## Code Review

- [ ] hi @kof, I need you to do
  - conceptual review (architecture, feature-correctness)
  - detailed review (read every line)
  - test it on preview

## Before requesting a review

- [ ] made a self-review
- [ ] added inline comments where things may be not obvious (the "why",
not "what")

## Before merging

- [ ] tested locally and on preview environment (preview dev login:
0000)
- [ ] updated [test
cases](https://github.com/webstudio-is/webstudio/blob/main/apps/builder/docs/test-cases.md)
document
- [ ] added tests
- [ ] if any new env variables are added, added them to `.env` file

Author: kof

apps/builder/app/builder/features/style-panel/sections/shared/input-popover.tsx

@@ -45,11 +45,13 @@ const Input = ({
 
   return (
     <CssValueInput
+      minWidth="6ch"
       styleSource={styleSource}
       property={property}
       value={value}
       intermediateValue={intermediateValue}
       getOptions={() => $availableUnitVariables.get()}
+      fieldSizing="content"
       onChange={(styleValue) => {
         setIntermediateValue(styleValue);
         const activeProperties = getActiveProperties();
@@ -176,7 +178,7 @@ export const InputPopover = ({
           description={propertyDescriptions[property]}
           properties={[property]}
         />
-        <Flex css={{ width: theme.spacing[20] }}>
+        <Flex css={{ maxWidth: theme.spacing[30] }}>
           <Input
             styleSource={styleSource}
             value={value}

apps/builder/app/builder/features/style-panel/shared/css-value-input/css-value-input.tsx

@@ -322,6 +322,7 @@ type CssValueInputProps = Pick<
   unitOptions?: UnitOption[];
   id?: string;
   placeholder?: string;
+  minWidth?: string;
 };
 
 const initialValue: IntermediateStyleValue = {
@@ -399,6 +400,7 @@ export const CssValueInput = ({
   text,
   unitOptions,
   placeholder,
+  minWidth = "2ch",
   ...props
 }: CssValueInputProps) => {
   const value = props.intermediateValue ?? props.value ?? initialValue;
@@ -921,7 +923,7 @@ export const CssValueInput = ({
             }
             css={{
               cursor: "default",
-              minWidth: "2em",
+              minWidth,
               "&:hover": {
                 [cssButtonDisplay]: "block",
               },