Interactive Area Build CLI Implementation Plan

Extract stage definitions, aliases, canonical ordering, and conflict validation from scripts/build-area.js into a shared CommonJS module.
Update build-area.js to consume the shared resolver without changing non-interactive semantics.
Add scripts/interactive-build.js with TTY detection, area discovery, raw-mode selection menus, cancellation handling, and child-process delegation to build-area.js.
Change package.json so npm run build calls the new interactive script while build:area remains unchanged.
Add focused Node tests for stage planning and non-TTY behavior; do not invoke Blender, QGIS, or a real area build in tests.
Run syntax checks, the focused tests, existing preflight/preview tests, and manually exercise the interactive flow in a TTY.