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/deps.py

@@ -11,11 +11,15 @@ from fastapi import Depends, Request
 from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
 
 from app.application import (
+    CreateCommentUseCase,
     CreatePostUseCase,
+    DeleteCommentUseCase,
     DeletePostUseCase,
     GetPostUseCase,
+    ListCommentsUseCase,
     ListPostsUseCase,
     PublishPostUseCase,
+    ToggleCommentLikeUseCase,
     TogglePostLikeUseCase,
     UpdatePostUseCase,
 )
@@ -31,6 +35,11 @@ ListPostsDep = FromDishka[ListPostsUseCase]
 PublishPostDep = FromDishka[PublishPostUseCase]
 ToggleLikeDep = FromDishka[TogglePostLikeUseCase]
 
+CreateCommentDep = FromDishka[CreateCommentUseCase]
+DeleteCommentDep = FromDishka[DeleteCommentUseCase]
+ListCommentsDep = FromDishka[ListCommentsUseCase]
+ToggleCommentLikeDep = FromDishka[ToggleCommentLikeUseCase]
+
 security = HTTPBearer(auto_error=False)