feat(issues): add Mark Done button to issue detail toolbar

Add a "Mark as done" button (CircleCheck icon) to the issue detail
header toolbar, positioned to the left of the Pin button. The button
is only visible when the issue status is not already done or cancelled.
Clicking it sets the issue status to "done" via the existing
handleUpdateField action.

packages/views/inbox/components/inbox-list-item.tsx

@@ -2,7 +2,7 @@
 
 import { StatusIcon } from "../../issues/components";
 import { ActorAvatar } from "../../common/actor-avatar";
-import { Archive } from "lucide-react";
+import { Archive, CircleCheck } from "lucide-react";
 import type { InboxItem } from "@multica/core/types";
 import { InboxDetailLabel } from "./inbox-detail-label";
 import { getInboxDisplayTitle } from "./inbox-display";
@@ -25,11 +25,13 @@ export function InboxListItem({
   isSelected,
   onClick,
   onArchive,
+  onDone,
 }: {
   item: InboxItem;
   isSelected: boolean;
   onClick: () => void;
   onArchive: () => void;
+  onDone?: () => void;
 }) {
   const displayTitle = getInboxDisplayTitle(item);
 
@@ -59,6 +61,26 @@ export function InboxListItem({
             </span>
           </div>
           <div className="flex shrink-0 items-center gap-1">
+            {onDone && (
+              <span
+                role="button"
+                tabIndex={-1}
+                title="Mark as done"
+                onClick={(e) => {
+                  e.stopPropagation();
+                  onDone();
+                }}
+                onKeyDown={(e) => {
+                  if (e.key === "Enter" || e.key === " ") {
+                    e.stopPropagation();
+                    onDone();
+                  }
+                }}
+                className="hidden rounded p-0.5 text-muted-foreground hover:bg-accent hover:text-info group-hover:inline-flex"
+              >
+                <CircleCheck className="h-3.5 w-3.5" />
+              </span>
+            )}
             <span
               role="button"
               tabIndex={-1}

packages/views/inbox/components/inbox-page.tsx

@@ -20,6 +20,7 @@ import {
   useArchiveAllReadInbox,
   useArchiveCompletedInbox,
 } from "@multica/core/inbox/mutations";
+import { useUpdateIssue } from "@multica/core/issues/mutations";
 import { IssueDetail } from "../../issues/components";
 import { useNavigation } from "../../navigation";
 import { toast } from "sonner";
@@ -117,6 +118,7 @@ export function InboxPage() {
   const archiveAllMutation = useArchiveAllInbox();
   const archiveAllReadMutation = useArchiveAllReadInbox();
   const archiveCompletedMutation = useArchiveCompletedInbox();
+  const updateIssueMutation = useUpdateIssue();
 
   // Auto-mark-read whenever a selected item is unread — covers both click-
   // to-select and URL-param-select (e.g. OS notification click on desktop).
@@ -145,6 +147,18 @@ export function InboxPage() {
     });
   };
 
+  const handleDone = (item: InboxItem) => {
+    if (!item.issue_id) return;
+    setSelectedKey("");
+    updateIssueMutation.mutate(
+      { id: item.issue_id, status: "done" },
+      { onError: () => toast.error("Failed to mark as done") },
+    );
+    archiveMutation.mutate(item.id, {
+      onError: () => toast.error("Failed to archive"),
+    });
+  };
+
   // Batch operations
   const handleMarkAllRead = () => {
     markAllReadMutation.mutate(undefined, {
@@ -235,6 +249,11 @@ export function InboxPage() {
           isSelected={(item.issue_id ?? item.id) === selectedKey}
           onClick={() => handleSelect(item)}
           onArchive={() => handleArchive(item.id)}
+          onDone={
+            item.issue_id && item.issue_status !== "done" && item.issue_status !== "cancelled"
+              ? () => handleDone(item)
+              : undefined
+          }
         />
       ))}
     </div>

packages/views/issues/components/issue-detail.tsx

@@ -9,6 +9,7 @@ import {
   ChevronDown,
   ChevronLeft,
   ChevronRight,
+  CircleCheck,
   MoreHorizontal,
   PanelRight,
   Pin,
@@ -511,6 +512,23 @@ export function IssueDetail({ issueId, onDelete, defaultSidebarOpen = true, layo
             </span>
           </div>
           <div className="flex items-center gap-1 shrink-0">
+            {issue.status !== "done" && issue.status !== "cancelled" && (
+              <Tooltip>
+                <TooltipTrigger
+                  render={
+                    <Button
+                      variant="ghost"
+                      size="icon-sm"
+                      className="text-muted-foreground"
+                      onClick={() => handleUpdateField({ status: "done" })}
+                    >
+                      <CircleCheck />
+                    </Button>
+                  }
+                />
+                <TooltipContent side="bottom">Mark as done</TooltipContent>
+              </Tooltip>
+            )}
             <Tooltip>
               <TooltipTrigger
                 render={