Share platform-split module types via .shared.ts files

Extract the prop/control types (and the video error classes) that were
duplicated between web implementations and their native throw-stubs into
sibling .shared.ts files, so both variants reference one definition and
cannot drift.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BCuMKXWHuyGoNhTVAHBMyk

src/view/com/composer/videos/SubtitleFilePicker.native.tsx

@@ -1,6 +1,5 @@
-export function SubtitleFilePicker(_props: {
-  onSelectFile: (file: File) => void
-  disabled?: boolean
-}): never {
+import {type SubtitleFilePickerProps} from './SubtitleFilePicker.shared'
+
+export function SubtitleFilePicker(_props: SubtitleFilePickerProps): never {
   throw new Error('SubtitleFilePicker is a web-only component')
 }

src/view/com/composer/videos/SubtitleFilePicker.shared.ts

@@ -0,0 +1,4 @@
+export type SubtitleFilePickerProps = {
+  onSelectFile: (file: File) => void
+  disabled?: boolean
+}

src/view/com/composer/videos/SubtitleFilePicker.tsx

@@ -9,14 +9,12 @@ import {atoms as a} from '#/alf'
 import {Button, ButtonIcon, ButtonText} from '#/components/Button'
 import {CC_Stroke2_Corner0_Rounded as CCIcon} from '#/components/icons/CC'
 import * as Toast from '#/components/Toast'
+import {type SubtitleFilePickerProps} from './SubtitleFilePicker.shared'
 
 export function SubtitleFilePicker({
   onSelectFile,
   disabled,
-}: {
-  onSelectFile: (file: File) => void
-  disabled?: boolean
-}) {
+}: SubtitleFilePickerProps) {
   const {_} = useLingui()
   const ref = useRef<HTMLInputElement>(null)