fix(synctex): gate sync buttons to LaTeX-only projects

Verso added 'qmd' and 'typ' to validRootDocExtensions, which caused
isValidTeXFile() to return true for Typst/Quarto files — enabling
SyncTeX UI controls for projects that never produce output.synctex.gz.

Replace the open-doc extension check in canSyncToPdf with a
LaTeX-only regex on the project root document path (tex|ltx|Rtex|Rnw),
and add the same guard in _syncToCode so PDF-click sync never fires
an API request for non-LaTeX projects.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/web/frontend/js/features/pdf-preview/hooks/use-synctex.ts

@@ -15,7 +15,6 @@ import { useEditorManagerContext } from '@/features/ide-react/context/editor-man
 import { useEditorOpenDocContext } from '@/features/ide-react/context/editor-open-doc-context'
 import useEventListener from '@/shared/hooks/use-event-listener'
 import { CursorPosition } from '@/features/ide-react/types/cursor-position'
-import { isValidTeXFile } from '@/main/is-valid-tex-file'
 import { PdfScrollPosition } from '@/shared/hooks/use-pdf-scroll-position'
 import {
   showFileErrorToast,
@@ -177,6 +176,12 @@ export default function useSynctex(): {
     positionRef.current = position
   }, [position])
 
+  // SyncTeX only works for LaTeX projects (requires output.synctex.gz).
+  // Typst and Quarto do not produce this file.
+  const LATEX_EXTENSIONS_RE = /\.(tex|ltx|Rtex|Rnw)$/i
+  const rootDocPath = rootDocId ? pathInFolder(rootDocId) : null
+  const isLatexRootDoc = rootDocPath ? LATEX_EXTENSIONS_RE.test(rootDocPath) : false
+
   const _syncToCode = useCallback(
     ({
       position = positionRef.current,
@@ -187,7 +192,7 @@ export default function useSynctex(): {
       selectText?: string
       visualOffset?: number
     }) => {
-      if (!position) {
+      if (!isLatexRootDoc || !position) {
         return
       }
 
@@ -240,6 +245,7 @@ export default function useSynctex(): {
         })
     },
     [
+      isLatexRootDoc,
       pdfFile,
       clsiServerId,
       projectId,
@@ -284,10 +290,10 @@ export default function useSynctex(): {
   }, [selectedEntities, setHasSingleSelectedDoc])
 
   const canSyncToPdf: boolean =
+    isLatexRootDoc &&
     hasSingleSelectedDoc &&
-    cursorPosition &&
-    openDocName &&
-    isValidTeXFile(openDocName)
+    !!cursorPosition &&
+    !!openDocName
 
   return {
     syncToCode,