Migration 0007 (spec said 0006 but 0006 was already roadmap_considering)
adds a single nullable metadata_text column to roadmap_items — a short
admin-set narrative cue shown on hover in the route cards. ~60 chars
suggested in admin helper text. Hidden in the UI when NULL.
db.ts: RoadmapItem type gains the field. createRoadmapItem + updateRoadmapItem
accept an optional metadata_text parameter. moveRoadmapItem passes it through
when swapping display_order between siblings so the helper preserves it.
Admin: /admin?tab=roadmap edit form gets a new 'Hover note' input under
the description, with the helper text and a 120-char hard cap. Empty
string saves as NULL.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
