remove labs docs (#1144)

## Overview

- Remove Labs docs since we are not surfacing in official LangChain docs
now

## Type of change

**Type:** Remove old docs

## Checklist
<!-- Put an 'x' in all boxes that apply -->
- [ ] I have read the [contributing guidelines](README.md)
- [ ] I have tested my changes locally using `docs dev`
- [ ] All code examples have been tested and work correctly
- [ ] I have used **root relative** paths for internal links
- [ ] I have updated navigation in `src/docs.json` if needed
- I have gotten approval from the relevant reviewers
- (Internal team members only / optional) I have created a preview
deployment using the [Create Preview Branch
workflow](https://github.com/langchain-ai/docs/actions/workflows/create-preview-branch.yml)

## Additional notes
<!-- Any other information that would be helpful for reviewers -->

Author: lnhsingh

.github/labeler.yml

@@ -33,13 +33,6 @@ oss:
       - src/oss/**
       - src/oss/**/*
 
-# Label for Labs documentation changes
-labs:
-  - changed-files:
-    - any-glob-to-any-file:
-      - src/labs/**
-      - src/labs/**/*
-
 # Label for Python-specific documentation
 python:
   - changed-files:

pipeline/core/builder.py

@@ -92,9 +92,6 @@ def build_all(self) -> None:
         logger.info("Building LangGraph JavaScript version...")
         self._build_langgraph_version("oss/javascript", "js")
 
-        logger.info("Building LangChain Labs content...")
-        self._build_unversioned_content("labs", "labs")
-
         logger.info("Building LangSmith content...")
         self._build_unversioned_content("langsmith", "langsmith")
 
@@ -305,7 +302,7 @@ def build_file(self, file_path: Path) -> None:
         if relative_path.parts[0] == "oss":
             self._build_oss_file(file_path, relative_path)
         # Check if this is unversioned content
-        elif relative_path.parts[0] in {"labs", "langsmith"}:
+        elif relative_path.parts[0] == "langsmith":
             self._build_unversioned_file(file_path, relative_path)
         # Handle shared files (images, docs.json, etc.)
         elif self.is_shared_file(file_path):
@@ -340,7 +337,7 @@ def _build_oss_file(self, file_path: Path, relative_path: Path) -> None:
             logger.info("Built JavaScript version: oss/javascript/%s", oss_relative)
 
     def _build_unversioned_file(self, file_path: Path, relative_path: Path) -> None:
-        """Build an unversioned file (langsmith, labs).
+        """Build an unversioned file (langsmith).
 
         Args:
             file_path: Path to the source file.
@@ -581,10 +578,10 @@ def _build_langgraph_version(self, output_dir: str, target_language: str) -> Non
         )
 
     def _build_unversioned_content(self, source_dir: str, output_dir: str) -> None:
-        """Build unversioned content (labs/, langsmith/).
+        """Build unversioned content (langsmith/).
 
         Args:
-            source_dir: Source directory name (e.g., "labs").
+            source_dir: Source directory name (e.g., "langsmith").
             output_dir: Output directory name (same as source_dir).
         """
         src_path = self.src_dir / source_dir