fix: improve query agent prompt wording for source content

Author: rejojer

openkb/agent/query.py

@@ -21,9 +21,10 @@
 2. Read relevant summary pages (summaries/) for document overviews.
    Note: summaries may omit details.
 3. Read concept pages (concepts/) for cross-document synthesis.
-4. When you need detailed source content, check the summary's full_text field:
-   - Short documents (full_text ends in .md): read_file(full_text) for the full text.
-   - PageIndex documents (full_text ends in .json): use get_page_content(doc_name, pages)
+4. When you need detailed source document content, each summary page has a
+   `full_text` frontmatter field with the path to the original document content:
+   - Short documents (doc_type: short): read_file with that path.
+   - PageIndex documents (doc_type: pageindex): use get_page_content(doc_name, pages)
      to read specific pages. The summary shows document tree structure with page ranges.
 5. Synthesise a clear, well-cited answer grounded in wiki content.