fix(showcase/dashboard): add maxPossible to parity-matrix DepthResult literals

Two object literals in parity-matrix.tsx ParityCategorySection were missing
the required maxPossible field on DepthResult, causing 'next build' to fail
with TS2322 and blocking the shell-dashboard production rebuild. Setting
maxPossible: 0 matches achieved: 0 for unwired cells (no probe → no ceiling),
which is consistent with how DepthChip renders an unshipped cell.

Cherry-picked from 1db2fbc on fix/dashboard-polish (Jordan Ritter); landing
standalone so the showcase deploy can rebuild from main without waiting on
the larger dashboard-polish branch.

Author: AlemTuzlak

showcase/shell-dashboard/src/components/parity-matrix.tsx

@@ -115,7 +115,12 @@ function ParityCategorySection({
           const refCell = cellIndex.get(`${referenceSlug}/${feature.id}`);
           const refDepth: DepthResult = refCell
             ? deriveDepth(refCell, liveStatus)
-            : { achieved: 0, isRegression: false, unsupported: false };
+            : {
+                achieved: 0,
+                maxPossible: 0,
+                isRegression: false,
+                unsupported: false,
+              };
           const refStatus = refDepth.unsupported
             ? "unsupported"
             : (refCell?.status ?? "unshipped");
@@ -141,7 +146,12 @@ function ParityCategorySection({
                 const cell = cellIndex.get(`${int.slug}/${feature.id}`);
                 const depth: DepthResult = cell
                   ? deriveDepth(cell, liveStatus)
-                  : { achieved: 0, isRegression: false, unsupported: false };
+                  : {
+                      achieved: 0,
+                      maxPossible: 0,
+                      isRegression: false,
+                      unsupported: false,
+                    };
                 const cellStatus = depth.unsupported
                   ? "unsupported"
                   : (cell?.status ?? "unshipped");