feat: add user authentication with separate login and register pages

- Custom User model with email as unique identifier (AUTH_USER_MODEL)

- POST /api/auth/register/ with email validation, password min 8 chars, duplicate rejection

- POST /api/auth/login/ returning JWT (access + refresh) tokens

- Passwords hashed via Django's make_password

- React LoginPage and RegisterPage with form validation

- AuthContext with useReducer for auth state management

- Axios API client with JWT token injection

- TypeScript conversion of frontend scaffold

api/accounts/admin.py

@@ -0,0 +1,39 @@
+from django.contrib import admin
+from django.contrib.auth.admin import UserAdmin as BaseUserAdmin
+
+from accounts.models import User
+
+
+@admin.register(User)
+class UserAdmin(BaseUserAdmin):
+    """Admin config for the custom User model."""
+
+    fieldsets = (
+        (None, {"fields": ("email", "password")}),
+        ("Personal info", {"fields": ("first_name", "last_name", "username")}),
+        (
+            "Permissions",
+            {
+                "fields": (
+                    "is_active",
+                    "is_staff",
+                    "is_superuser",
+                    "groups",
+                    "user_permissions",
+                ),
+            },
+        ),
+        ("Important dates", {"fields": ("last_login", "date_joined")}),
+    )
+    add_fieldsets = (
+        (
+            None,
+            {
+                "classes": ("wide",),
+                "fields": ("email", "password1", "password2"),
+            },
+        ),
+    )
+    list_display = ("email", "first_name", "last_name", "is_staff")
+    search_fields = ("email", "first_name", "last_name")
+    ordering = ("email",)