Update admin theme/layout and refresh README details.

Align the project baseline with the latest admin interface styling and layout structure while documenting setup and usage updates in README.

apps/api/app/db/seed.py

@@ -0,0 +1,98 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime
+
+from app.core.config import settings
+from app.core.security import hash_password
+from app.modules.content.repository import create_page, get_page_by_slug
+from app.modules.users.repository import create_user, get_user_by_email
+
+
+def _ensure_user(email: str, password: str, role: str, is_superuser: bool, status: str):
+    from app.modules.users import repository
+
+    user = get_user_by_email(email)
+    if user:
+        changed = False
+        if user.role != role:
+            user.role = role
+            changed = True
+        if user.is_superuser != is_superuser:
+            user.is_superuser = is_superuser
+            changed = True
+        if user.status != status:
+            user.status = status
+            changed = True
+        if user.email_verified_at is None and status == "active":
+            user.email_verified_at = datetime.now(UTC)
+            changed = True
+        if changed:
+            repository.update_user(user)
+        return user
+
+    user = create_user(
+        email=email,
+        password_hash=hash_password(password),
+        role=role,
+        is_superuser=is_superuser,
+        status=status,
+    )
+    user.email_verified_at = datetime.now(UTC)
+    repository.update_user(user)
+    return user
+
+
+def run_seed(include_demo_pages: bool = True) -> None:
+    admin = _ensure_user(
+        email="admin@compton.example",
+        password=settings.admin_initial_password,
+        role="admin",
+        is_superuser=True,
+        status="active",
+    )
+    _ensure_user(
+        email="user@compton.example",
+        password=settings.demo_user_password,
+        role="user",
+        is_superuser=False,
+        status="active",
+    )
+    _ensure_user(
+        email="ops@compton.example",
+        password=settings.demo_ops_password,
+        role="admin",
+        is_superuser=False,
+        status="active",
+    )
+
+    if not include_demo_pages:
+        return
+
+    demo_pages = [
+        {
+            "slug": "about",
+            "title": "О бренде",
+            "body": "<p>Compton — платформа Organic Tech.</p>",
+        },
+        {
+            "slug": "privacy",
+            "title": "Политика конфиденциальности",
+            "body": "<p>Мы обрабатываем персональные данные согласно политике.</p>",
+        },
+        {
+            "slug": "terms",
+            "title": "Условия использования",
+            "body": "<p>Используя сервис, вы принимаете условия.</p>",
+        },
+    ]
+
+    for page in demo_pages:
+        if get_page_by_slug(page["slug"], include_draft=True):
+            continue
+        create_page(
+            slug=page["slug"],
+            title=page["title"],
+            body=page["body"],
+            status="published",
+            author_id=admin.id,
+        )