Add multi-tenant SaaS: business signup, owner/branch-manager/staff hierarchy, full tenant isolation

.gitignore

@@ -1,6 +1,38 @@
-node_modules/
-.next/
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
 .env
+.env*.local
 .env.local
-.env.*.local
-*.log
+.env.development.local
+.env.test.local
+.env.production.local
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts