fix: normalize Windows path suggestions

.changeset/normalize-windows-path-suggestions.md

@@ -0,0 +1,5 @@
+---
+"@jmfederico/pi-web": patch
+---
+
+Normalize allowed external path suggestions on Windows so configured absolute paths use platform separators consistently.

src/server/workspaces/fileSuggestions.ts

@@ -206,8 +206,8 @@ function pathSuggestionPrefix(query: string): { directoryPrefix: string; searchP
 
 function appendRequestPath(base: string, name: string): string {
   if (base === "") return name;
-  if (hasTrailingPathSeparator(base)) return `${base}${name}`;
   if (isAbsolute(base) || win32.isAbsolute(base)) return join(base, name);
+  if (hasTrailingPathSeparator(base)) return `${base}${name}`;
   return `${base}/${name}`;
 }