Migrate soldeer dependency `rain-interpreter-interface` → `rainlang-interface`

[thedavidmeister]

The interface repo was renamed rain.interpreter.interface → rainlang.interface and republishes on Soldeer as rainlang-interface (see rainlanguage/rainlang.interface#116, follow-up to rainlanguage/rainlang.interface#105).

This repo pins the old Soldeer name — ~8 references to rain-interpreter-interface (dep + versioned rain-interpreter-interface-<ver>/… import paths).

Action

Migrate the soldeer dependency and all import paths from rain-interpreter-interface → rainlang-interface@0.2.0:

• update foundry.toml [dependencies] / soldeer.lock,
• update remappings.txt and the versioned rain-interpreter-interface-*/… import paths in src//test//script/,
• rebuild pointers/bindings as needed and green CI.

Blocked on

rainlanguage/rainlang.interface#117 — rainlang-interface@0.2.0 must be published first (the Soldeer project needs registering; the first publish currently fails). The old rain-interpreter-interface@0.1.x stays published, so nothing breaks until this migration lands.