Add TypeORMExtractor for @Entity-decorated models

[itsflaid]

Context
Same reserved slot in extractors/index.ts (// new TypeORMExtractor()).

Scope
Parse classes decorated with @Entity(), fields with @Column(), relations from @OneToMany / @ManyToOne / @ManyToMany decorators.

Acceptance criteria

• canHandle() detects TypeORM usage (import from typeorm, presence of @Entity())
• extract() maps decorated fields to FieldInfo, decorated relations to isRelation/isList
• Registered in EXTRACTORS
• source union extended with "typeorm"
• Tests added