feat: dashboard, Convex auth, UI components, and LemonSpace branding

- Add dashboard shell with auth integration
- Wire Better Auth / Convex (client, server, HTTP routes)
- Add shadcn-style UI primitives and logo assets
- Update global styles and landing page
- Add internal docs (.docs)

Made-with: Cursor

convex/auth.ts

@@ -0,0 +1,36 @@
+import { createClient, type GenericCtx } from "@convex-dev/better-auth";
+import { convex } from "@convex-dev/better-auth/plugins";
+import { components } from "./_generated/api";
+import { DataModel } from "./_generated/dataModel";
+import { query } from "./_generated/server";
+import { betterAuth } from "better-auth/minimal";
+import authConfig from "./auth.config";
+
+const siteUrl = process.env.SITE_URL!;
+
+// Component Client — stellt Adapter, Helper und Auth-Methoden bereit
+export const authComponent = createClient<DataModel>(components.betterAuth);
+
+// Auth Factory — wird pro Request aufgerufen (Convex ist request-scoped)
+export const createAuth = (ctx: GenericCtx<DataModel>) => {
+  return betterAuth({
+    baseURL: siteUrl,
+    trustedOrigins: [siteUrl],
+    database: authComponent.adapter(ctx),
+    emailAndPassword: {
+      enabled: true,
+      requireEmailVerification: false, // Später auf true → useSend Integration
+    },
+    plugins: [
+      convex({ authConfig }),
+    ],
+  });
+};
+
+// Helper Query: Aktuellen User abrufen (nutzbar in Frontend via useQuery)
+export const getCurrentUser = query({
+  args: {},
+  handler: async (ctx) => {
+    return authComponent.safeGetAuthUser(ctx);
+  },
+});