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/modules/content/repository.py

@@ -0,0 +1,105 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime
+from uuid import uuid4
+
+from sqlalchemy import select
+
+from app.core.database import session_scope
+from app.modules.content.models import ContentPage
+
+ALLOWED_PAGE_STATUSES = {"draft", "published"}
+
+
+def _detach(db, instance):
+    db.refresh(instance)
+    db.expunge(instance)
+    return instance
+
+
+def list_published_pages() -> list[ContentPage]:
+    with session_scope() as db:
+        pages = list(
+            db.scalars(select(ContentPage).where(ContentPage.status == "published").order_by(ContentPage.slug))
+        )
+        return [_detach(db, page) for page in pages]
+
+
+def list_all_pages() -> list[ContentPage]:
+    with session_scope() as db:
+        pages = list(db.scalars(select(ContentPage).order_by(ContentPage.slug)))
+        return [_detach(db, page) for page in pages]
+
+
+def get_page_by_slug(slug: str, include_draft: bool = False) -> ContentPage | None:
+    with session_scope() as db:
+        page = db.scalar(select(ContentPage).where(ContentPage.slug == slug))
+        if not page:
+            return None
+        if include_draft or page.status == "published":
+            return _detach(db, page)
+        return None
+
+
+def get_page_by_id(page_id: str) -> ContentPage | None:
+    with session_scope() as db:
+        page = db.get(ContentPage, page_id)
+        if not page:
+            return None
+        return _detach(db, page)
+
+
+def create_page(
+    slug: str,
+    title: str,
+    body: str,
+    status: str,
+    author_id: str,
+) -> ContentPage:
+    if status not in ALLOWED_PAGE_STATUSES:
+        raise ValueError("INVALID_STATUS")
+    with session_scope() as db:
+        page = ContentPage(
+            id=str(uuid4()),
+            slug=slug,
+            title=title,
+            body=body,
+            status=status,
+            author_id=author_id,
+            published_at=datetime.now(UTC) if status == "published" else None,
+        )
+        db.add(page)
+        db.flush()
+        return _detach(db, page)
+
+
+def update_page(
+    page_id: str,
+    title: str | None,
+    body: str | None,
+    status: str | None,
+) -> ContentPage:
+    with session_scope() as db:
+        page = db.get(ContentPage, page_id)
+        if not page:
+            raise KeyError(page_id)
+        if title:
+            page.title = title
+        if body:
+            page.body = body
+        if status:
+            if status not in ALLOWED_PAGE_STATUSES:
+                raise ValueError("INVALID_STATUS")
+            page.status = status
+            if status == "published" and page.published_at is None:
+                page.published_at = datetime.now(UTC)
+        page.updated_at = datetime.now(UTC)
+        db.flush()
+        return _detach(db, page)
+
+
+def delete_page(page_id: str) -> None:
+    with session_scope() as db:
+        page = db.get(ContentPage, page_id)
+        if page:
+            db.delete(page)