Rev 11: the maze has no wall at zero, and moving sectors carry everything

Relocate Sector could never land a sector west or north of the origin
— placements the physical game allows by simply sliding the whole map
across the table. The coordinate grid still cannot go negative, but
now it does not need to: a sector may land at negative coordinates
and the whole maze renormalizes, zero-anchoring on both axes (which
also pulls the maze snug when the origin corner is vacated, instead
of leaving a blank band). The client offers the new landings as ghost
slots on every side, verified slot-for-slot against engine truth.

The move also closes a real gap: remapState never carried creatures,
boobytrap tokens, glue, open safes, or dimensional warp tokens when a
sector relocated or rotated — they were left hovering at their old
coordinates. Sectors now carry everything standing on them. Both
changes ride rules rev 11; older ledgers replay their flaws intact,
as replay determinism demands.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/web/src/Board.svelte

@@ -45,12 +45,16 @@
   } = $props();
 
   const SECTOR = 5;
-  /** Ghost slots can lie beyond the assembled maze; the canvas grows to hold them. */
+  /** Ghost slots can lie beyond the assembled maze — on any side, including
+   * negative coordinates (the maze renormalizes after the landing). The
+   * canvas grows in whichever direction holds them. */
+  const minBx = $derived(Math.min(0, ...(ghostSlots ?? []).map((g) => g.x)) * CELL - 8);
+  const minBy = $derived(Math.min(0, ...(ghostSlots ?? []).map((g) => g.y)) * CELL - 8);
   const boundsW = $derived(
-    Math.max(view.board.width, ...(ghostSlots ?? []).map((g) => g.x + SECTOR)) * CELL + 16,
+    Math.max(view.board.width, ...(ghostSlots ?? []).map((g) => g.x + SECTOR)) * CELL + 8 - minBx,
   );
   const boundsH = $derived(
-    Math.max(view.board.height, ...(ghostSlots ?? []).map((g) => g.y + SECTOR)) * CELL + 16,
+    Math.max(view.board.height, ...(ghostSlots ?? []).map((g) => g.y + SECTOR)) * CELL + 8 - minBy,
   );
 
 
@@ -171,7 +175,7 @@
      derive one from the viewBox alone and collapses the board to 0x0 inside
      a max-height flex column. Doubled so CSS max-* caps still govern. -->
 <svg
-  viewBox={`-8 -8 ${boundsW} ${boundsH}`}
+  viewBox={`${minBx} ${minBy} ${boundsW} ${boundsH}`}
   width={boundsW * 2}
   height={boundsH * 2}
   class="board"