feat(extraction): add Solidity language support (.sol) (#374, #648) (#1170)

Contracts/libraries/interfaces, structs, enums, modifiers, events, errors,
state variables; call edges for emit/revert/modifier guards/base-constructor
chains/library calls; is-inheritance with implements reclassification;
import resolution. Validated on solmate, solady, openzeppelin-contracts.

Lands #667.

Co-authored-by: naiba <hi@nai.ba>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

src/extraction/languages/index.ts

@@ -32,6 +32,7 @@ import { cfqueryExtractor } from './cfquery';
 import { cobolExtractor } from './cobol';
 import { vbnetExtractor } from './vbnet';
 import { erlangExtractor } from './erlang';
+import { solidityExtractor } from './solidity';
 
 export const EXTRACTORS: Partial<Record<Language, LanguageExtractor>> = {
   typescript: typescriptExtractor,
@@ -61,4 +62,5 @@ export const EXTRACTORS: Partial<Record<Language, LanguageExtractor>> = {
   cobol: cobolExtractor,
   vbnet: vbnetExtractor,
   erlang: erlangExtractor,
+  solidity: solidityExtractor,
 };