Add Cancel button to inventory QR scan usage page

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Web/Views/Inventory/Scan.cshtml

@@ -168,7 +168,7 @@
         }
         .reason-pill.selected { border-color: var(--purple); background: #f3effe; color: var(--purple); font-weight: 600; }
 
-        /* ── Submit ──────────────────────────────────── */
+        /* ── Submit / Cancel ─────────────────────────── */
         .btn-submit {
             width: 100%;
             padding: 16px;
@@ -183,6 +183,22 @@
         }
         .btn-submit:disabled { opacity: .6; }
         .btn-submit:active { background: var(--purple-dark); }
+        .btn-cancel {
+            display: block;
+            width: 100%;
+            padding: 14px;
+            background: #fff;
+            color: var(--muted);
+            border: 1.5px solid var(--border);
+            border-radius: 10px;
+            font-size: 16px;
+            font-weight: 600;
+            cursor: pointer;
+            margin-top: 10px;
+            text-align: center;
+            text-decoration: none;
+        }
+        .btn-cancel:active { background: #f0f0f0; }
 
         .error-banner {
             margin: 0 16px 16px;
@@ -319,10 +335,11 @@
             </div>
         </div>
 
-        <div style="margin: 0 16px">
+        <div style="margin: 0 16px 8px">
             <button type="submit" class="btn-submit" id="submitBtn">
                 Save Usage Log
             </button>
+            <a href="/Inventory/Details/@item!.Id" class="btn-cancel">Cancel</a>
         </div>
     </form>