fix(docs[ext]): Restrict tool label registration to tool sections only

why: _register_tool_labels iterated every section in every document,
registering non-tool headings (e.g. "Inspect", "Act") in the
StandardDomain. This risked label collisions with other extensions.
what:
- Replace fallback to title_node.astext() with continue
- Only register sections whose title starts with a nodes.literal child
  (the pattern used by fastmcp-tool directive output)

Author: tony

docs/_ext/fastmcp_autodoc.py

@@ -814,16 +814,18 @@ def _register_tool_labels(app: Sphinx, doctree: nodes.document) -> None:
             continue
         section_id = section["ids"][0]
         if section.children and isinstance(section[0], nodes.title):
-            # Extract just the tool name from the first literal child,
-            # ignoring the safety badge that follows it.
+            # Only register sections whose title starts with a literal
+            # (tool sections generated by fastmcp-tool have nodes.literal
+            # as the first title child).  Non-tool sections (e.g. "Inspect",
+            # "Act") don't need site-wide labels.
             title_node = section[0]
             tool_name = ""
             for child in title_node.children:
                 if isinstance(child, nodes.literal):
                     tool_name = child.astext()
                     break
             if not tool_name:
-                tool_name = title_node.astext()
+                continue
             domain.anonlabels[section_id] = (docname, section_id)
             domain.labels[section_id] = (docname, section_id, tool_name)