Adds DEFAULT_LAYOUT + IMAGE_FRAME_ROWS constants (fractional art/text window
anchors), a ZoneEditor component for bounding-box layout editing in the
designer, and expands the custom-frames/games CRUD API surface to support
frame image storage and retrieval. Custom card designer pages wire these
together with the existing PNG export pipeline.
See .convoys/card-designer-image-frames.md for scope tracking.
- custom_frames: per-user frames with full 9-slot palette (JSONB),
unique names; designer frame picker lists them alongside starters,
click to use, edit/delete via inline editor with live preview
- custom_symbols: upload cost icons (PNG/WebP/SVG, 2MB) keyed by short
code; re-uploading a code replaces the old icon; ManaPips renders
icon pips for {CODE} tokens with graceful text fallback
- custom_cards.custom_frame_id links designs to custom frames; API GETs
join and nest the palette; deleting a frame falls back to starter
- migration 1787700511000
