PICK SEA crucifix grid: rename CSS position classes + remove dead code

Stage 1 — free 'cross':
- sea-cross-cell → sea-crucifix-cell (template, Jasmine fixture, SCSS)

Stage 2 — semantic position names:
- sea-pos-past → sea-pos-leave; grid-area: past → leave
- sea-pos-center → sea-pos-core; grid-area: center → core
- sea-pos-future → sea-pos-loom; grid-area: future → loom
- sea-pos-root → sea-pos-lay; grid-area: root → lay
- grid-template-areas updated to match
- sea-pos-crossing removed (dead code — no element ever carried it)

Jasmine + 35 ITs green.

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Sonnet 4.6 <noreply@anthropic.com>

src/static_src/scss/_card-deck.scss

@@ -778,8 +778,8 @@ html.sea-open .sea-modal-wrap {
     display: grid;
     grid-template-areas:
         ".      crown   .      "
-        "past   center  future "
-        ".      root    .      ";
+        "leave  core    loom   "
+        ".      lay     .      ";
     grid-template-columns: 1fr 1fr 1fr;
     grid-template-rows: auto auto auto;
     gap: 0.5rem;
@@ -787,13 +787,12 @@ html.sea-open .sea-modal-wrap {
     justify-items: center;
 }
 
-.sea-cross-cell { display: flex; align-items: center; justify-content: center; }
+.sea-crucifix-cell { display: flex; align-items: center; justify-content: center; }
 .sea-pos-crown    { grid-area: crown; }
-.sea-pos-past     { grid-area: past; }
-.sea-pos-center   { grid-area: center; }
-.sea-pos-future   { grid-area: future; }
-.sea-pos-root     { grid-area: root; }
-.sea-pos-crossing { grid-area: crossing; }
+.sea-pos-leave     { grid-area: leave; }
+.sea-pos-core   { grid-area: core; }
+.sea-pos-loom   { grid-area: loom; }
+.sea-pos-lay     { grid-area: lay; }
 
 $sea-card-w: 4rem;
 $sea-card-h: 6.5rem;
@@ -874,8 +873,8 @@ $sea-card-h: 6.5rem;
     box-shadow: 0 0 0.5rem 0.25rem rgba(var(--ninUser), 0.35), 0 0 0.4rem rgba(0, 0, 0, 0.85);
 }
 
-// Cover + Cross — absolutely overlaid on the Sig card in .sea-pos-center
-.sea-pos-center { position: relative; }
+// Cover + Cross — absolutely overlaid on the Sig card in .sea-pos-core
+.sea-pos-core { position: relative; }
 
 .sea-pos-cover,
 .sea-pos-cross {