Tint the kanban inbox column lighter than the status columns

New --inbox-bg token (light and dark) applied via .kanban__col--inbox so the
inbox reads as distinct from "To do" / "Doing" / "Done".

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

web/src/style.css

@@ -11,6 +11,8 @@
   --warn-bg: #fff4e5;
   --warn-border: #f0c48a;
   --error: #b3261e;
+  /* Kanban inbox column: a touch lighter than a status column (var(--bg)). */
+  --inbox-bg: #fcfcfd;
   color-scheme: light dark;
 }
 
@@ -24,6 +26,7 @@
     --warn-bg: #2e2415;
     --warn-border: #6b5220;
     --error: #f2b8b5;
+    --inbox-bg: #202027;
   }
 }
 
@@ -406,6 +409,10 @@ h1 {
   padding: 0.75rem;
 }
 
+.kanban__col--inbox {
+  background: var(--inbox-bg);
+}
+
 .kanban__head {
   display: flex;
   align-items: center;

web/src/views/ProjectView.vue

@@ -344,7 +344,12 @@ async function onCreateInbox() {
         <p v-if="cards.loading && !cards.loaded" class="muted">Loading…</p>
 
         <div v-else class="kanban">
-          <section v-for="column in board" :key="column.key" class="kanban__col">
+          <section
+            v-for="column in board"
+            :key="column.key"
+            class="kanban__col"
+            :class="{ 'kanban__col--inbox': column.statusId === null }"
+          >
             <header class="kanban__head">
               <span class="kanban__title">{{ column.title }}</span>
               <span class="kanban__count">{{ column.cards.length }}</span>