Implement GitHub issue close reasons and tabbed comment composer (#5235)

- Support closing GitHub issues with specific reasons ('completed', 'not planned', or duplicate) via main-process mutations and gh CLI wrappers.
- Replace the legacy comment composer with a tabbed layout supporting a real-time markdown preview, image/attachment inputs, and state transition buttons.
- Refactor assignee and label popovers into dedicated reusable components to clean up the item dialog.

src/main/github/issues.ts

@@ -235,10 +235,19 @@ export async function updateIssue(
   if (updates.state) {
     await acquire()
     try {
-      const cmd = updates.state === 'closed' ? 'close' : 'reopen'
-      await ghExecFileAsync(['issue', cmd, String(issueNumber), '--repo', repo], {
-        ...ghOptions
-      })
+      if (updates.state === 'closed') {
+        const closeArgs = ['issue', 'close', String(issueNumber), '--repo', repo]
+        if (updates.stateReason === 'completed') {
+          closeArgs.push('--reason', 'completed')
+        } else if (updates.stateReason === 'not_planned') {
+          closeArgs.push('--reason', 'not planned')
+        } else if (updates.stateReason === 'duplicate' && updates.duplicateOf) {
+          closeArgs.push('--duplicate-of', String(updates.duplicateOf))
+        }
+        await ghExecFileAsync(closeArgs, ghOptions)
+      } else {
+        await ghExecFileAsync(['issue', 'reopen', String(issueNumber), '--repo', repo], ghOptions)
+      }
     } catch (err) {
       const stderr = err instanceof Error ? err.message : String(err)
       // Treat "already closed/open" as a no-op

src/main/github/project-view/mutations.ts

@@ -171,15 +171,29 @@ export async function updateIssueBySlug(
   if (!args.updates || typeof args.updates !== 'object') {
     return { ok: false, error: { type: 'validation_error', message: 'Updates required.' } }
   }
-  const { title, body, state, addLabels, removeLabels, addAssignees, removeAssignees } =
-    args.updates
+  const {
+    title,
+    body,
+    state,
+    stateReason,
+    duplicateOf,
+    addLabels,
+    removeLabels,
+    addAssignees,
+    removeAssignees
+  } = args.updates
 
   // Title / body / state go through PATCH /repos/{owner}/{repo}/issues/{n}.
   // Labels/assignees go through their dedicated endpoints.
   const base = `repos/${args.owner}/${args.repo}/issues/${args.number}`
 
   // 1) PATCH body
-  if (title !== undefined || body !== undefined || state !== undefined) {
+  if (
+    title !== undefined ||
+    body !== undefined ||
+    state !== undefined ||
+    stateReason !== undefined
+  ) {
     const patchArgs: string[] = ['-X', 'PATCH', base]
     if (title !== undefined) {
       patchArgs.push('--raw-field', `title=${title}`)
@@ -190,6 +204,12 @@ export async function updateIssueBySlug(
     if (state !== undefined) {
       patchArgs.push('--raw-field', `state=${state}`)
     }
+    if (stateReason !== undefined) {
+      patchArgs.push('--raw-field', `state_reason=${stateReason}`)
+    }
+    if (duplicateOf !== undefined) {
+      patchArgs.push('--raw-field', `duplicate_of=${duplicateOf}`)
+    }
     const r = await runRest<unknown>(patchArgs)
     if (!r.ok) {
       return { ok: false, error: r.error }