Task: B4: Collapse refdata and refdata-cpp into a single component

A single refdata component entry in the component catalogue discovers all ores.refdata.*.org entity files (excluding junctions and module index) and dispatches SQL, C++, messaging, and Qt profiles from one component. The refdata-cpp component entry is removed.

• compass codegen entity –component refdata generates SQL, C++, and Qt output identical to running –component refdata and –component refdata-cpp separately before this change
• Dead models_dir entries are removed from the catalogue
• No other component references refdata-cpp
• All existing codegen regression tests pass with zero diff

(Implementation strategy. Written when work starts; key decisions are distilled into the parent story's * Decisions at close, but the plan itself stays — it is the historical record of what we did.)