chore: pre-provision fixes (PII removal, .gitignore, branch rename)

- Remove author PII from sample article frontmatter
- Add graph/intermediate/ to .gitignore
- Rename master → main for CI workflow compatibility

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: lqdev

.gitignore

@@ -48,3 +48,6 @@ Thumbs.db
 htmlcov/
 .tox/
 .nox/
+
+# Generated graph intermediates
+graph/intermediate/

content/2026/04/what-is-a-knowledge-graph.md

@@ -3,7 +3,7 @@ title: "What is a Knowledge Graph?"
 date_published: "2026-04-04"
 date_modified: "2026-04-04"
 authors:
-  - name: "Luis"
+  - name: "Author Name"
 tags: ["knowledge-graph", "sparql", "linked-data", "markdown"]
 about:
   - "https://schema.org/KnowledgeGraph"