Move the research route domain into the canonical routes/research/ subpackage while preserving the legacy routes.research_routes import path through a sys.modules compatibility shim.
The moved canonical module is behavior-preserving, app wiring now imports the canonical route setup function, source-introspection tests point at the new canonical path, and shim regression coverage pins legacy/canonical same-object behavior plus string-targeted monkeypatch reach-through.
Refs #4082.
Refs #4071.
