* M12: stamps stick to the objects they land on
A stamp sticks to the topmost object under its centre (BoardItem::Stamp gains an optional on, left out when empty so older files open with stamps on nothing) and the board's normalize pass carries it when that object moves or turns, once when both move together. A stamp dragged onto another object sticks to that one, off everything to nothing; one whose object is deleted stays where it is. Gap 24.
* M12: the object a stamp will stick to is highlighted
While the stamp tool is over an object, or a stamp is dragged over one, the object it will stick to is outlined with the canvas's hover outline (Overlay::stamp_target, found by the same stamp_target as board.stamp and settle_stamps). A drag no longer drops what it moves into the auto layout of a sticky, shape with text or table: board objects take no drops; a stamp already inside its sticky moves with it once. Builds on #1671. Gap 24.
* M12: boards dot grid, re-attaching connector ends, curved connectors
Board pages draw a dot grid in the canvas render, after the page colour
and under the layers (figcraft_render::Dots), thinned out when zoomed out
and coloured from the theme's ink against the page. A selected connector
shows its ends as handles; dragging one onto an object re-attaches it,
onto empty canvas leaves it free (board.reattach, one undo step, also
over MCP). Connectors can be curved, and elbows go around the objects
they join when the short way would cross them.
* M12: boards dot grid: blending a dot in a function of its own (Sonar)
Board files (File > New board) with sticky notes, shapes with text, connectors that follow what they join (straight or elbow, arrowheads, labels), marker, highlighter and eraser, and stamps; a board toolbar and a contextual bar; the Design panel hidden on boards, Prototype and Dev Mode refused there. Boards are ordinary FigCraft files built from ordinary layers, so saving, undo, export, MCP and live sessions work unchanged. File tabs, recent files and Open files show a pen nib for design files and a note for boards (original icons drawn in code).
BFlat