fix: access before initialization error (#1342)

## 📜 Description

Fixed error.

```sh
Metro error: Cannot access 'clampedScrollTarget' before initialization

  ReferenceError: Cannot access 'clampedScrollTarget' before initialization
```

## 💡 Motivation and Context

It seems like `export function` produces:

<img width="774" height="673" alt="image"
src="https://github.com/user-attachments/assets/6faf2e2d-de9c-4565-8adb-dba1c5cdc13d"
/>

While `export const` produces:

<img width="1000" height="663" alt="image"
src="https://github.com/user-attachments/assets/23cf8661-d418-4e55-8bf9-4314d591d732"
/>
...
<img width="1069" height="323" alt="image"
src="https://github.com/user-attachments/assets/ac30e296-7afc-4ec7-891f-bbe774ae6457"
/>

So with first case we try to export function that hasn't been declared
(though `function` should be hoisted?). Anyway across the package we
often use `arrow functions` and it doesn't cause issues, so let's
continue to use it.

In this PR I re-worked `helpers` file and used arrow functions instead
of regular functions.

## 📢 Changelog

<!-- High level overview of important changes -->
<!-- For example: fixed status bar manipulation; added new types
declarations; -->
<!-- If your changes don't affect one of platform/language below - then
remove this platform/language -->

### JS

- use `export const` instead of `export function`;
- use arrow functions in `helpers`;

## 🤔 How Has This Been Tested?

Tested in LegendList repo.

## 📸 Screenshots (if appropriate):

|Before|After|
|-------|-----|
|<img width="774" height="673" alt="image"
src="https://github.com/user-attachments/assets/6faf2e2d-de9c-4565-8adb-dba1c5cdc13d"
/>|<img width="1000" height="663" alt="image"
src="https://github.com/user-attachments/assets/23cf8661-d418-4e55-8bf9-4314d591d732"
/>|

## 📝 Checklist

- [x] CI successfully passed
- [x] I added new mocks and corresponding unit-tests if library API was
changed

Author: kirillzyusko

src/components/KeyboardChatScrollView/useChatKeyboard/helpers.ts

@@ -18,11 +18,11 @@ const AT_END_THRESHOLD = 20;
  * getEffectiveHeight(150, 300, 50); // 125
  * ```
  */
-export function getEffectiveHeight(
+export const getEffectiveHeight = (
   height: number,
   targetKeyboardHeight: number,
   offset: number,
-): number {
+): number => {
   "worklet";
 
   if (offset === 0 || targetKeyboardHeight === 0) {
@@ -34,7 +34,7 @@ export function getEffectiveHeight(
     [0, targetKeyboardHeight],
     [0, Math.max(targetKeyboardHeight - offset, 0)],
   );
-}
+};
 
 /**
  * Check whether the scroll view is at the end of its content.
@@ -54,20 +54,20 @@ export function getEffectiveHeight(
  * const atEndInverted = isScrollAtEnd(5, 800, 2000, true); // true (5 <= 20)
  * ```
  */
-export function isScrollAtEnd(
+export const isScrollAtEnd = (
   scrollOffset: number,
   layoutHeight: number,
   contentHeight: number,
   inverted: boolean = false,
-): boolean {
+): boolean => {
   "worklet";
 
   if (inverted) {
     return scrollOffset <= AT_END_THRESHOLD;
   }
 
   return scrollOffset + layoutHeight >= contentHeight - AT_END_THRESHOLD;
-}
+};
 
 /**
  * Decide whether content should be shifted based on the keyboard lift behavior.
@@ -81,10 +81,10 @@ export function isScrollAtEnd(
  * shouldShiftContent("whenAtEnd", false); // false
  * ```
  */
-export function shouldShiftContent(
+export const shouldShiftContent = (
   behavior: KeyboardLiftBehavior,
   isAtEnd: boolean,
-): boolean {
+): boolean => {
   "worklet";
 
   switch (behavior) {
@@ -97,7 +97,7 @@ export function shouldShiftContent(
     case "persistent":
       return true;
   }
-}
+};
 
 /**
  * Compute the clamped scroll target for non-inverted lists.
@@ -112,18 +112,18 @@ export function shouldShiftContent(
  * clampedScrollTarget(100, 300, 1000, 800); // 400
  * ```
  */
-export function clampedScrollTarget(
+export const clampedScrollTarget = (
   offsetBeforeScroll: number,
   keyboardHeight: number,
   contentHeight: number,
   layoutHeight: number,
-): number {
+): number => {
   "worklet";
 
   const maxScroll = Math.max(contentHeight - layoutHeight + keyboardHeight, 0);
 
   return Math.min(Math.max(offsetBeforeScroll + keyboardHeight, 0), maxScroll);
-}
+};
 
 /**
  * Compute contentOffset.y for iOS lists.
@@ -140,14 +140,14 @@ export function clampedScrollTarget(
  * computeIOSContentOffset(100, 300, 1000, 800, false); // 400
  * ```
  */
-export function computeIOSContentOffset(
+export const computeIOSContentOffset = (
   relativeScroll: number,
   keyboardHeight: number,
   contentHeight: number,
   layoutHeight: number,
   inverted: boolean,
   extraContentPadding: number = 0,
-): number {
+): number => {
   "worklet";
 
   if (inverted) {
@@ -165,4 +165,4 @@ export function computeIOSContentOffset(
   );
 
   return Math.min(Math.max(keyboardHeight + relativeScroll, 0), maxScroll);
-}
+};