feat(web): first-time user onboarding flow

New user signs in → /dashboard (user) → hits server-side getMyMeshes → 0
results → redirects to /dashboard/meshes/new?onboarding=1. Create-mesh
page renders a welcome banner explaining what a mesh is. After submit,
if ?onboarding=1 was set, the form bounces to
/dashboard/meshes/[id]/invite?onboarding=1 instead of the mesh detail
page. Invite page renders a "🎉 Mesh created" banner with the
`claudemesh join <link>` CLI snippet.

The onboarding flag is URL-driven — no persistence needed, dismissal
happens naturally when the user navigates away.

Also rewrites the /dashboard (user) home page from the placeholder
"Welcome to your Dashboard" TurboStarter card grid to a claudemesh-
native view: top 6 meshes with badges, All meshes / New mesh CTAs.
Removes the unused Card/Icons imports.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/modules/mesh/create-mesh-form.tsx

@@ -40,7 +40,9 @@ const slugify = (s: string) =>
     .replace(/^-+|-+$/g, "")
     .slice(0, 40);
 
-export const CreateMeshForm = () => {
+export const CreateMeshForm = ({
+  onboarding = false,
+}: { onboarding?: boolean } = {}) => {
   const router = useRouter();
   const form = useForm<CreateMyMeshInput>({
     resolver: zodResolver(createMyMeshInputSchema),
@@ -70,7 +72,11 @@ export const CreateMeshForm = () => {
         form.setError("slug", { message: res.error });
         return;
       }
-      router.push(pathsConfig.dashboard.user.meshes.mesh(res.id));
+      router.push(
+        onboarding
+          ? `${pathsConfig.dashboard.user.meshes.invite(res.id)}?onboarding=1`
+          : pathsConfig.dashboard.user.meshes.mesh(res.id),
+      );
     } catch (e) {
       form.setError("root", {
         message: e instanceof Error ? e.message : "Failed to create mesh.",