D8.12-C BimCraft: use an element as something else — a wall as a panel, a slab as a road or shelf, a roof as a ramp

Keep the drawing tool's geometry and editing but report the element as another IFC class (and predefined type), so schedules, takeoff, Problems and the IFC export count a slab drawn as a road as a road, not a floor. A "Report as" field in Properties (search of IFC classes that fit the shape), one undo step, round-trips through IFC2X3 and IFC4; schedules group by the reported class. The requester's point: the other program files these as generic models and its schedules stay wrong. Part of D8.12.

**Implementation started 2026-11-02** (0.9 top-5 pick #2, hardest first; session `bim-views-09`, log docs/0.9-sessions/bim-views-09.md). Status moves to Partly built or Built only when the code is reachable and tested (rule 49).