fix(provenance): resolve merge conflicts, fix session API, move schemas

- Resolve all merge conflict markers in provenance.py, app.py, .gitignore
- Revert broken session.get_nodes()/get_edges() to session.graph.nodes/edges
- Keep undirected=True ego_graph fix for upstream ancestor traversal
- Add direction field to ProvenanceEdge (upstream/downstream/lateral)
- Group lineage edges in _render_markdown by direction section
- Move ProvenanceNode/ProvenanceEdge/ProvenanceResponse to schemas.py
- Restore complete router import set in app.py (sparql, vocabulary, etc.)

Co-authored-by: Sameer6305 <sameer6305@users.noreply.github.com>
Co-authored-by: KaifAhmad1 <mohammadk78600@gmail.com>

.gitignore

@@ -111,11 +111,9 @@ sample_data/
 # Test Results
 test_results.txt
 
-<<<<<<< HEAD
 # Frontend workspace artifacts
 semantica-explorer/
 node_modules/
-=======
+
 # Frontend build artifacts (generated by Vite — do not track in git)
 semantica/static/
->>>>>>> upstream/main