feat(adr): implement ADR-0109, ADR-0110, and ADR-0111

- ADR-0109: Incremental Background AST Indexing & Differential Graph Updates via Tree-Sitter
- ADR-0110: Real-Time SSE Live Activity & Log Stream (/api/events/stream)
- ADR-0111: Automated Stale Symbol Pruning & Graph Tombstoning (sweep_graph_health auto_prune_stale_files)

server/src/indexer.rs

@@ -143,7 +143,12 @@ pub async fn start_background_indexer(state: Arc<MemoryState>) {
     });
 }
 
-fn extract_chunks(node: Node, code: &str, chunks: &mut Vec<(String, String, String)>, ext: &str) {
+pub fn extract_chunks(
+    node: Node,
+    code: &str,
+    chunks: &mut Vec<(String, String, String)>,
+    ext: &str,
+) {
     extract_chunks_with_parent(node, code, chunks, ext, None, 0);
 }