Add page_exists, blog_post_exists, and title lookup methods to Confluence Cloud (closes #581)

The Server implementation had these methods but the Cloud module was
missing them. Adds get_page_by_title, get_blog_post_by_title,
page_exists, and blog_post_exists to match Server API parity.

Author: star7js

atlassian/confluence/cloud/__init__.py

@@ -60,6 +60,24 @@ def get_content_ancestors(self, content_id, **kwargs):
         """Get ancestor content."""
         return self.get(f"content/{content_id}/ancestors", **kwargs)
 
+    def get_page_by_title(self, space_key, title, **kwargs):
+        """Get page by title and space key."""
+        return self.get("content", params={"spaceKey": space_key, "title": title, "type": "page", **kwargs})
+
+    def get_blog_post_by_title(self, space_key, title, **kwargs):
+        """Get blog post by title and space key."""
+        return self.get("content", params={"spaceKey": space_key, "title": title, "type": "blogpost", **kwargs})
+
+    def page_exists(self, space_key, title, **kwargs):
+        """Check if page exists."""
+        result = self.get_page_by_title(space_key, title, **kwargs)
+        return len(result.get("results", [])) > 0
+
+    def blog_post_exists(self, space_key, title, **kwargs):
+        """Check if blog post exists."""
+        result = self.get_blog_post_by_title(space_key, title, **kwargs)
+        return len(result.get("results", [])) > 0
+
     # Space Management
     def get_spaces(self, **kwargs):
         """Get all spaces."""