feat: add Google/GitHub social login for Demo environment (GRO-531)

- auth.ts: add google/github social providers from better-auth/social-providers
- auth.ts: add getActiveProviders() to enumerate configured OAuth/social providers
- index.ts: add /api/auth/providers public endpoint for frontend
- App.tsx: update LoginPage to show Google/GitHub buttons based on /api/auth/providers response

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/index.ts

@@ -2,7 +2,7 @@ import { serve } from "@hono/node-server";
 import { Hono } from "hono";
 import { logger } from "hono/logger";
 import { cors } from "hono/cors";
-import { getAuth, initAuth } from "./lib/auth.js";
+import { getAuth, initAuth, getActiveProviders } from "./lib/auth.js";
 import { clientsRouter } from "./routes/clients.js";
 import { petsRouter } from "./routes/pets.js";
 import { servicesRouter } from "./routes/services.js";
@@ -92,6 +92,11 @@ app.get("/api/setup/status", async (c) => {
   return c.json({ needsSetup: !superUser });
 });
 
+// Public auth providers endpoint — no auth required, tells frontend which login options are available
+app.get("/api/auth/providers", async (c) => {
+  return c.json({ providers: getActiveProviders() });
+});
+
 // Protected API routes
 const api = app.basePath("/api");
 api.use("*", authMiddleware);

apps/api/src/lib/auth.ts

@@ -1,6 +1,7 @@
 import { betterAuth } from "better-auth";
 import { drizzleAdapter } from "better-auth/adapters/drizzle";
 import { genericOAuth } from "better-auth/plugins";
+import { google, github } from "better-auth/social-providers";
 import { getDb, authProviderConfig, eq } from "@groombook/db";
 import { decryptSecret } from "@groombook/db";
 
@@ -27,6 +28,21 @@ export function getAuthPromise() {
   return authInitPromise;
 }
 
+/** Returns which OAuth/social providers are configured via env vars. */
+export function getActiveProviders(): string[] {
+  const providers: string[] = [];
+  if (process.env.GOOGLE_CLIENT_ID && process.env.GOOGLE_CLIENT_SECRET) {
+    providers.push("google");
+  }
+  if (process.env.GITHUB_CLIENT_ID && process.env.GITHUB_CLIENT_SECRET) {
+    providers.push("github");
+  }
+  if (process.env.OIDC_ISSUER && process.env.OIDC_CLIENT_ID && process.env.OIDC_CLIENT_SECRET) {
+    providers.push("authentik");
+  }
+  return providers;
+}
+
 /**
  * Re-initializes the Better-Auth instance after auth config changes.
  *
@@ -152,6 +168,23 @@ export async function initAuth(): Promise<void> {
       console.log("[auth] Using env var config (no DB config found)");
     }
 
+    const hasGoogle = !!(process.env.GOOGLE_CLIENT_ID && process.env.GOOGLE_CLIENT_SECRET);
+    const hasGitHub = !!(process.env.GITHUB_CLIENT_ID && process.env.GITHUB_CLIENT_SECRET);
+
+    const socialPlugins = [];
+    if (hasGoogle) {
+      socialPlugins.push(google({
+        clientId: process.env.GOOGLE_CLIENT_ID!,
+        clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
+      }));
+    }
+    if (hasGitHub) {
+      socialPlugins.push(github({
+        clientId: process.env.GITHUB_CLIENT_ID!,
+        clientSecret: process.env.GITHUB_CLIENT_SECRET!,
+      }));
+    }
+
     // Build Better-Auth instance using resolved config
     authInstance = betterAuth({
       database: drizzleAdapter(db, {
@@ -179,7 +212,8 @@ export async function initAuth(): Promise<void> {
             },
           ],
         }),
-            ],
+        ...socialPlugins,
+      ],
       session: {
         expiresIn: 60 * 60 * 24 * 7, // 7 days
         updateAge: 60 * 60 * 24, // 1 day