fix: correct schema syntax for SurrealDB 2.3.10 compatibility

Updated schema to use proper SurrealDB 2.3.10 syntax based on official
documentation:

- Removed duplicate ANALYZER definitions
- Fixed ASSERT statements to include NONE checks: ASSERT $value = NONE OR array::len($value) = N
- Made metadata fields FLEXIBLE TYPE to handle dynamic objects
- Corrected HNSW index syntax with proper parameters
- Ensured id fields use built-in record types (not string)

Schema is now fully compatible with SurrealDB 2.3.10 and properly
handles record IDs, graph traversal, and HNSW vector search.

Author: jruokola

schema/codegraph.surql

@@ -315,7 +315,7 @@ DEFINE INDEX IF NOT EXISTS idx_symbol_embeddings_node
 DEFINE INDEX IF NOT EXISTS idx_symbol_embeddings_edge
     ON TABLE symbol_embeddings COLUMNS source_edge_id;
 
--- =============================================================================
+#=============================================================================
 -- FUNCTIONS
 -- =============================================================================