feat(icons): added square-kanban-plus icon (#4688)

* feat(icons): added `square-kanban-plus` icon

Adds square-kanban-plus for issue #4416.
Also updates emoji category icon reference after smile rename.

* chore(icons): expand square-kanban-plus metadata from PR suggestions

Apply curated tags, categories, and use-cases from automated
metadata review suggestions.

* Apply design from @jguddas

* Update contributors and use cases in square-kanban-plus.json

Added new contributors and updated use cases to improve clarity.

---------

Co-authored-by: Eric Fennis <eric.fennis@gmail.com>

icons/square-kanban-plus.json

@@ -0,0 +1,39 @@
+{
+  "$schema": "../icon.schema.json",
+  "contributors": [
+    "KesleyDavid",
+    "jguddas"
+  ],
+  "use-cases": [
+    "Adding a new kanban board in project management apps",
+    "Creating a new board from an empty state or dashboard",
+    "Toolbar action to open a new agile board or sprint view",
+    "Indicating add-column or add-board affordances next to kanban views",
+    "Empty-state call-to-action to set up a kanban board",
+    "Onboarding step to prompt creation of a first project board"
+  ],
+  "tags": [
+    "board",
+    "project",
+    "add",
+    "create",
+    "plus",
+    "agile",
+    "tickets",
+    "issues",
+    "productivity",
+    "columns",
+    "workflow",
+    "planning",
+    "dashboard",
+    "workspace",
+    "collaboration",
+    "cards"
+  ],
+  "categories": [
+    "charts",
+    "development",
+    "design",
+    "layout"
+  ]
+}

icons/square-kanban-plus.svg

@@ -0,0 +1,18 @@
+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <path d="M12 7v4" />
+  <path d="M12.354 21H5a2 2 0 01-2-2V5a2 2 0 012-2h14a2 2 0 012 2v7.354" />
+  <path d="M15 18h6" />
+  <path d="M16 7v4.536" />
+  <path d="M18 21v-6" />
+  <path d="M8 7v7" />
+</svg>