feat(core-models): per-language adapters onto the canonical model

[rahlk]

Adapters mapping the existing per-language models onto the canonical core:

• JType / JCallable / ... → canonical
• PyModule / PyCallable / ... → canonical
• TSClass / TSCallable / TSSynthesizedCallable / ... → canonical
• CFunction / CTranslationUnit / ... → canonical

Non-breaking: legacy models keep working; the adapters power URI resolution and the fluent query core. One adapter module per language, individually testable — naturally splits into one PR per language off a shared design.

Part of #194. Branch: feat/issue-<n>.