fix: address max-effort review findings

- clamp LLM-derived page indices in _get_text_of_pages and
  get_text_of_pdf_pages_with_labels; dedupe get_text_of_pdf_pages
- guard _normalize_tree and folders/documents iterations against
  explicit nulls in cloud API responses
- coerce cloud OCR page numbers to int before filtering in
  get_page_content
- folder cache: raise on missing folder id instead of caching None;
  stop caching name-not-found so later lookups can succeed
- defang doc_id in agent doc-context prompt
- append api-key hint to 401 errors (request, legacy and streaming
  paths)
- remove stale legacy JSON workspace sample data unreadable by the
  SQLite storage

pageindex/cloud_api.py

@@ -6,7 +6,7 @@ from typing import Any, Iterator
 
 import requests
 
-from .errors import PageIndexAPIError
+from .errors import AUTH_HINT, PageIndexAPIError
 
 # Single source of truth for the cloud API base URL — imported by the modern
 # CloudBackend (as API_BASE) and PageIndexClient so a staging/migration change
@@ -47,7 +47,10 @@ class LegacyCloudAPI:
             raise PageIndexAPIError(f"{error_prefix}: {e}") from e
 
         if response.status_code != 200:
-            raise PageIndexAPIError(f"{error_prefix}: {response.text}")
+            msg = f"{error_prefix}: {response.text}"
+            if response.status_code == 401:
+                msg += f" — {AUTH_HINT}"
+            raise PageIndexAPIError(msg)
         return response
 
     def submit_document(