fix: handle Windows path separators in attachment and session path display

Use regex split /[/\\]/ instead of split('/') to handle both
forward and backslash separators. Affects ChatMessage attachment
URL extraction and session path display in SessionPreview and
SessionsSheet components.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: devartifex

src/lib/components/chat/ChatMessage.svelte

@@ -34,8 +34,8 @@
         const a = att as { type: 'file'; path: string; name: string };
         const ext = a.name.split('.').pop()?.toLowerCase() ?? '';
         const isImage = IMAGE_EXTENSIONS.has(ext);
-        // Extract uploadId and filename from path: /tmp/copilot-uploads/{uploadId}/{filename}
-        const parts = a.path.split('/');
+        // Extract uploadId and filename from path (handles both / and \ separators)
+        const parts = a.path.split(/[/\\]/);
         const filename = parts[parts.length - 1];
         const uploadId = parts[parts.length - 2];
         const url = `/api/upload/files/${encodeURIComponent(uploadId)}/${encodeURIComponent(filename)}`;

src/lib/components/sessions/SessionPreview.svelte

@@ -23,7 +23,7 @@
 
   function formatPath(cwd: string | undefined): string {
     if (!cwd) return '';
-    const parts = cwd.split('/').filter(Boolean);
+    const parts = cwd.split(/[/\\]/).filter(Boolean);
     return parts.length > 3 ? `…/${parts.slice(-3).join('/')}` : cwd;
   }
 </script>

src/lib/components/sessions/SessionsSheet.svelte

@@ -140,7 +140,7 @@
   function formatPath(cwd: string | undefined): string {
     if (!cwd) return '';
     // Show last 2 path segments
-    const parts = cwd.split('/').filter(Boolean);
+    const parts = cwd.split(/[/\\]/).filter(Boolean);
     return parts.length > 2 ? `…/${parts.slice(-2).join('/')}` : cwd;
   }
 </script>