Extract IMPORTS/IMPLEMENTS/INHERITS edges (multi-language)

[ajianaz]

Goal

Extract and store non-CALLS edge types during indexing: IMPORTS, IMPLEMENTS, INHERITS, CHILD_OF.

Context

#429 wires up store_kg_edges() for the edges table but focuses on CALLS only (migration from call_graph). This issue extends extraction to other edge kinds.

Per-Language Extraction Rules

Edge Kind	Rust	Python	TypeScript	Go
IMPORTS	use crate::foo	import foo	import { x } from 'y'	import "pkg"
IMPLEMENTS	impl Trait for Struct	class inherits ABC	implements Interface	interface satisfaction
INHERITS	derive(Parent)	class Child(Parent)	class C extends P	struct embedding
CHILD_OF	nested mods	nested classes	namespaces	sub-packages

Implementation

1. Extend src/index/extract.rs per language
2. Rust: parse use, impl ... for, #[derive]
3. Python: parse import, from ... import, class X(Y)
4. TypeScript: parse import, implements, extends
5. Go: parse import, struct embedding
6. Store via store_kg_edges() with appropriate EdgeKind

Acceptance

• SELECT kind, COUNT(*) FROM edges GROUP BY kind shows IMPORTS + IMPLEMENTS
• cora query "* <- IMPORTS <- main" works after indexing
• No regression in indexing speed (< 10% overhead)

Depends On

• Wire up store_kg_edges() — populate edges table #429 (wire up edges table)

Estimated Effort

1-2 weeks

[ajianaz]

Depends On

• Wire up store_kg_edges() — populate edges table #429 — Wire up store_kg_edges() (edges table must exist)