Task: Collapse components: merge refdata and refdata-cpp into a single component

A single refdata component entry drives discovery and dispatch for all entity files; refdata-cpp is removed from the component catalogue.

• The component catalogue has one entry for refdata with a single ores.refdata.*.org discovery glob.
• The dead models_dir entries for both former components are removed.
• compass codegen regenerate –component refdata –profile all regenerates all C++, SQL, and Qt artefacts correctly.
• No reference to refdata-cpp remains in the component catalogue or in compass commands.

(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.)