class_hierarchy misses most subclasses across files #683

Description

class_hierarchy (via analyze_code_relationships) only finds child classes defined in the same file or immediately adjacent files. It misses the majority of subclasses spread across a large project.

Steps to Reproduce

1. Index a Django project with a mixin class MontageTestCase in tools/montage_test/testcases.py
2. Verify with grep that 19 classes inherit from MontageTestCase across the src/ directory
3. Query: analyze_code_relationships(query_type="class_hierarchy", target="MontageTestCase")

Expected Result

All 19 child classes found.

Actual Result

Only 3 child classes returned — all from the same file or one nearby test file. The other 16 subclasses across src/ are missed entirely.

Analysis

The INHERITS relationships in the graph appear incomplete. The AST parser likely only resolves inheritance within the same file or module, not across the full project. Classes that from montage_test.testcases import MontageTestCase in other files are not linked.

Environment

• CGC version: 0.2.14
• Database: Neo4j
• Project: ~1400 Python files, Django monolith