fix(tldraw): export TldrawUiTranslationProvider and dedupe missing-translation warning (tldraw#8909)

In order to let consumers render components like
`TldrawSelectionForeground` without pulling in the full
`TldrawUiContextProvider` (and its icon preloading), this PR promotes
`TldrawUiTranslationProvider`, `AssetUrlsProvider`, and `useAssetUrls`
from `@internal` to `@public`. It also deduplicates the "No translation
messages found" warning so it only logs once per session instead of once
per component that calls `useTranslation`, and rewords the message to
point developers at `TldrawUiTranslationProvider` as an alternative.

Closes tldraw#6236

Consumers can now do:

```tsx
<AssetUrlsProvider assetUrls={...}>
  <TldrawUiTranslationProvider locale="en">
    <TldrawSelectionForeground ... />
  </TldrawUiTranslationProvider>
</AssetUrlsProvider>
```

### Change type

- [x] `bugfix`

### Test plan

1. Render a component that uses `useTranslation` (e.g.
`TldrawSelectionForeground`) outside of `TldrawUiContextProvider`.
2. Confirm the "No translation messages found" warning prints **once**,
not once per consumer.
3. Wrap the same component in
`<AssetUrlsProvider><TldrawUiTranslationProvider locale="en">` and
confirm the warning is silenced and translations resolve.

- [ ] Unit tests
- [ ] End to end tests

### Release notes

- Export `TldrawUiTranslationProvider`, `AssetUrlsProvider`, and
`useAssetUrls` as public API so `TldrawSelectionForeground` and similar
components can be used without `TldrawUiContextProvider`.
- Only log the missing-translation warning once per session instead of
once per `useTranslation` consumer.

### API changes

- Changed `TldrawUiTranslationProvider` from `@internal` to `@public
@react`.
- Changed `AssetUrlsProvider` from `@internal` to `@public @react`.
- Changed `useAssetUrls` from `@internal` to `@public`.

### Code changes

| Section         | LOC change |
| --------------- | ---------- |
| Core code       | +18 / -6   |
| Automated files | +3 / -3    |

Author: mimecuvalo

packages/tldraw/api-report.api.md

@@ -478,7 +478,7 @@ export const ASPECT_RATIO_TO_VALUE: Record<ASPECT_RATIO_OPTION, number>;
 // @public (undocumented)
 export function AssetToolbarItem(): JSX.Element;
 
-// @internal (undocumented)
+// @public
 export function AssetUrlsProvider({ assetUrls, children }: {
     assetUrls: TLUiAssetUrls;
     children: React.ReactNode;
@@ -4364,7 +4364,7 @@ export interface TldrawUiTooltipProviderProps {
     children: React_3.ReactNode;
 }
 
-// @internal
+// @public
 export function TldrawUiTranslationProvider({ overrides, locale, children }: TLUiTranslationProviderProps): JSX.Element;
 
 // @public (undocumented)
@@ -6309,7 +6309,7 @@ export function useA11y(): TLUiA11yContextType;
 // @public (undocumented)
 export function useActions(): TLUiActionsContextType;
 
-// @internal (undocumented)
+// @public (undocumented)
 export function useAssetUrls(): TLUiAssetUrls;
 
 // @public (undocumented)

packages/tldraw/src/lib/ui/context/asset-urls.tsx

@@ -7,7 +7,12 @@ type UiAssetUrlsContextType = TLUiAssetUrls | null
 
 const AssetUrlsContext = createContext<UiAssetUrlsContextType>(null)
 
-/** @internal */
+/**
+ * Provides asset URLs (icons, fonts, translations, embed icons) to the editor's UI.
+ * Required when using `TldrawUiTranslationProvider` without `TldrawUiContextProvider`.
+ *
+ * @public @react
+ */
 export function AssetUrlsProvider({
 	assetUrls,
 	children,
@@ -37,7 +42,7 @@ export function AssetUrlsProvider({
 	return <AssetUrlsContext.Provider value={assetUrls}>{children}</AssetUrlsContext.Provider>
 }
 
-/** @internal */
+/** @public */
 export function useAssetUrls() {
 	const assetUrls = useContext(AssetUrlsContext)
 	if (!assetUrls) {

packages/tldraw/src/lib/ui/hooks/useTranslation/useTranslation.tsx

@@ -1,3 +1,4 @@
+import { warnOnce } from '@tldraw/editor'
 import * as React from 'react'
 import { useAssetUrls } from '../../context/asset-urls'
 import { DEFAULT_TRANSLATION } from './defaultTranslation'
@@ -36,9 +37,11 @@ export function useCurrentTranslation() {
 }
 
 /**
- * Provides a translation context to the editor.
+ * Provides a translation context to the editor. Wrap this around components that use
+ * `useTranslation` (such as `TldrawSelectionForeground`) when you don't want to use the
+ * full `TldrawUiContextProvider`. Must be rendered inside an `AssetUrlsProvider`.
  *
- * @internal
+ * @public @react
  */
 export function TldrawUiTranslationProvider({
 	overrides,
@@ -115,7 +118,9 @@ export function useTranslation() {
 
 	React.useEffect(() => {
 		if (!translation?.messages) {
-			console.warn('No translation messages found, falling back to default translation.')
+			warnOnce(
+				'No translation messages found, falling back to default translation. Wrap your app in <TldrawUiContextProvider>, or in both <AssetUrlsProvider> and <TldrawUiTranslationProvider>, to provide translations.'
+			)
 		}
 	}, [translation?.messages])