Monorepo: consolidate 7 repos into one

Combines shared, blog, market, cart, events, federation, and account
into a single repository. Eliminates submodule sync, sibling model
copying at build time, and per-app CI orchestration.

Changes:
- Remove per-app .git, .gitmodules, .gitea, submodule shared/ dirs
- Remove stale sibling model copies from each app
- Update all 6 Dockerfiles for monorepo build context (root = .)
- Add build directives to docker-compose.yml
- Add single .gitea/workflows/ci.yml with change detection
- Add .dockerignore for monorepo build context
- Create __init__.py for federation and account (cross-app imports)

blog/bp/post/services/entry_associations.py

@@ -0,0 +1,60 @@
+from __future__ import annotations
+
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from shared.services.registry import services
+
+
+async def toggle_entry_association(
+    session: AsyncSession,
+    post_id: int,
+    entry_id: int
+) -> tuple[bool, str | None]:
+    """
+    Toggle association between a post and calendar entry.
+    Returns (is_now_associated, error_message).
+    """
+    post = await services.blog.get_post_by_id(session, post_id)
+    if not post:
+        return False, "Post not found"
+
+    is_associated = await services.calendar.toggle_entry_post(
+        session, entry_id, "post", post_id,
+    )
+    return is_associated, None
+
+
+async def get_post_entry_ids(
+    session: AsyncSession,
+    post_id: int
+) -> set[int]:
+    """
+    Get all entry IDs associated with this post.
+    Returns a set of entry IDs.
+    """
+    return await services.calendar.entry_ids_for_content(session, "post", post_id)
+
+
+async def get_associated_entries(
+    session: AsyncSession,
+    post_id: int,
+    page: int = 1,
+    per_page: int = 10
+) -> dict:
+    """
+    Get paginated associated entries for this post.
+    Returns dict with entries (CalendarEntryDTOs), total_count, and has_more.
+    """
+    entries, has_more = await services.calendar.associated_entries(
+        session, "post", post_id, page,
+    )
+    total_count = len(entries) + (page - 1) * per_page
+    if has_more:
+        total_count += 1  # at least one more
+
+    return {
+        "entries": entries,
+        "total_count": total_count,
+        "has_more": has_more,
+        "page": page,
+    }