feat: add comments feature with nested replies and recursive rendering

Implement full comments system: domain entities (Comment, CommentLike),
value objects (CommentContent), use cases (CRUD, like toggle), SQLAlchemy
repository, API v1 endpoints, web UI with comment form and nested replies,
i18n translations (EN/RU/FR/DE), and E2E tests.

Fix nested reply (reply-to-reply) not displaying — the flat reply_comments
dict was only queried for top-level comment IDs, so deeply nested replies
were saved to DB (incrementing comment count) but never rendered. Switch
to a recursive Jinja2 macro that renders any nesting depth.

app/presentation/api/v1/comments.py

@@ -0,0 +1,131 @@
+"""Comments API routes.
+
+This module defines FastAPI routes for comment operations including
+CRUD and like/unlike toggle.
+"""
+
+from uuid import UUID
+
+from dishka.integrations.fastapi import DishkaRoute
+from fastapi import APIRouter, status
+
+from app.presentation.api.deps import (
+    CreateCommentDep,
+    CurrentRoleDep,
+    CurrentUserDep,
+    DeleteCommentDep,
+    ListCommentsDep,
+    ToggleCommentLikeDep,
+)
+from app.presentation.schemas import (
+    CommentCreateSchema,
+    CommentLikeResponseSchema,
+    CommentResponseSchema,
+)
+
+router = APIRouter(tags=["comments"], route_class=DishkaRoute)
+
+
+@router.post(
+    "/posts/{post_id}/comments",
+    response_model=CommentResponseSchema,
+    status_code=status.HTTP_201_CREATED,
+    summary="Create a comment on a post",
+)
+async def create_comment(
+    post_id: UUID,
+    schema: CommentCreateSchema,
+    use_case: CreateCommentDep,
+    current_user_id: CurrentUserDep,
+) -> CommentResponseSchema:
+    """Create a comment on a blog post.
+
+    Args:
+        post_id: UUID of the post to comment on.
+        schema: Comment creation data.
+        use_case: CreateCommentUseCase dependency.
+        current_user_id: Authenticated user ID.
+
+    Returns:
+        CommentResponseSchema with created comment data.
+    """
+    result = await use_case.execute(
+        post_id=post_id,
+        author_id=current_user_id,
+        content=schema.content,
+        parent_id=schema.parent_id,
+    )
+    return CommentResponseSchema(**result.__dict__)
+
+
+@router.get(
+    "/posts/{post_id}/comments",
+    response_model=list[CommentResponseSchema],
+    summary="List comments for a post",
+)
+async def list_comments(
+    post_id: UUID,
+    use_case: ListCommentsDep,
+) -> list[CommentResponseSchema]:
+    """Get all comments for a blog post.
+
+    Args:
+        post_id: UUID of the post.
+        use_case: ListCommentsUseCase dependency.
+
+    Returns:
+        List of CommentResponseSchema for the post.
+    """
+    results = await use_case.execute(post_id=post_id)
+    return [CommentResponseSchema(**r.__dict__) for r in results]
+
+
+@router.delete(
+    "/comments/{comment_id}",
+    status_code=status.HTTP_204_NO_CONTENT,
+    summary="Delete a comment",
+)
+async def delete_comment(
+    comment_id: UUID,
+    use_case: DeleteCommentDep,
+    current_user_id: CurrentUserDep,
+    role: CurrentRoleDep,
+) -> None:
+    """Delete a comment.
+
+    Users can delete their own comments.
+
+    Args:
+        comment_id: UUID of the comment to delete.
+        use_case: DeleteCommentUseCase dependency.
+        current_user_id: Authenticated user ID.
+        role: Current user role.
+    """
+    await use_case.execute(comment_id=comment_id, user_id=current_user_id)
+
+
+@router.post(
+    "/comments/{comment_id}/like",
+    response_model=CommentLikeResponseSchema,
+    summary="Toggle like on a comment",
+)
+async def toggle_comment_like(
+    comment_id: UUID,
+    use_case: ToggleCommentLikeDep,
+    current_user_id: CurrentUserDep,
+) -> CommentLikeResponseSchema:
+    """Toggle like/unlike on a comment.
+
+    If the user already liked the comment, the like is removed (unlike).
+    Otherwise, a new like is added.
+
+    Args:
+        comment_id: UUID of the comment.
+        use_case: ToggleCommentLikeUseCase dependency.
+        current_user_id: Authenticated user ID.
+
+    Returns:
+        CommentLikeResponseSchema with updated like_count.
+    """
+    result = await use_case.execute(comment_id, current_user_id)
+    return CommentLikeResponseSchema(id=result.id, like_count=result.like_count)