Add nested posts UI (#5)

## Summary
- Cut hunt, question, submission, voting, hiding, and profile flows over to unified posts
- Render nested replies with permission-aware inline Reply/Edit controls and edited markers
- Add post profile queries and the author index migration they depend on

Co-authored-by: codegirl-007 <s.raide@gmail.com>

internal/web/posts.go

@@ -59,7 +59,7 @@ func (s *Server) handleCreatePost(w http.ResponseWriter, r *http.Request) {
 			http.NotFound(w, r)
 			return
 		}
-		if !user.Admin() && user.ID != threadRoot.AuthorID {
+		if !canReplyToThread(user, threadRoot) {
 			http.Error(w, "forbidden", http.StatusForbidden)
 			return
 		}
@@ -175,3 +175,42 @@ func canEditPost(user *store.User, post *store.Post) bool {
 	}
 	return user.ID == post.AuthorID
 }
+
+func canReplyToThread(user *store.User, root *store.Post) bool {
+	return user != nil &&
+		root != nil &&
+		root.PostState != store.PostStateHidden &&
+		(user.Admin() || user.ID == root.AuthorID)
+}
+
+func postLabel(post *store.Post) string {
+	if post == nil {
+		return ""
+	}
+	if post.ParentID == nil {
+		return "Question"
+	}
+	if post.AuthorRole == store.RoleAdmin {
+		return "Shop response"
+	}
+	return "Homeowner"
+}
+
+func postDepthClass(depth int) string {
+	switch depth {
+	case 0:
+		return "root"
+	case 1:
+		return "branch"
+	default:
+		return "deep"
+	}
+}
+
+func postPointers(posts []store.Post) []*store.Post {
+	out := make([]*store.Post, len(posts))
+	for i := range posts {
+		out[i] = &posts[i]
+	}
+	return out
+}