feat(panel): clickable Branch/PR links + branch copy button

The Branch value in the task-detail card and the Branch/PR badges in the task
list were static text. Make them open the real thing on GitHub, keeping their
exact look:

- New repo-url helper normalizes a project git_url (https/ssh, with/without
  .git) into web URLs for a branch (/tree/<branch>) and PR (/pull/<n>),
  returning null so callers fall back to a plain label.
- Task-detail Branch card: the branch is now a link to its GitHub tree URL and
  gains a copy button (reuses CopyButton); PR was already linked.
- List-row git badge (git-status-badge): the PR badge links to task.pr_url
  (or the built pull URL) and the Branch badge links to the branch tree URL.
  The row's click handler already ignores <a> clicks, so opening a branch/PR
  never toggles the row. git_url is threaded via a projectGitUrls map from the
  tasks page, alongside the existing projectNames map.

panel typecheck + eslint clean.

panel/src/components/tasks/git-status-badge.tsx

@@ -1,24 +1,61 @@
 "use client";
 
+import type { ReactNode } from "react";
 import { GitBranch, GitPullRequest, FileCheck } from "lucide-react";
 import { Badge } from "@/components/ui/badge";
 import { Task, TaskStatus } from "@/types";
+import { branchUrl, pullUrl } from "@/lib/repo-url";
 
 interface GitStatusBadgeProps {
   task: Task;
   compact?: boolean;
+  /** Project git_url — used to build the clickable branch / PR links. */
+  repoUrl?: string | null;
 }
 
-export function GitStatusBadge({ task, compact = true }: GitStatusBadgeProps) {
+/**
+ * Wrap a badge in an external link when a URL is available, otherwise render it
+ * plain. The badge keeps its exact look; the link only adds the click target
+ * (and a subtle hover). The parent row's click handler ignores `<a>` clicks, so
+ * opening a branch/PR never also toggles the row.
+ */
+function MaybeLink({
+  href,
+  children,
+}: {
+  href: string | null;
+  children: ReactNode;
+}) {
+  if (!href) return <>{children}</>;
+  return (
+    <a
+      href={href}
+      target="_blank"
+      rel="noopener noreferrer"
+      title="Open in GitHub"
+      className="inline-flex transition-opacity hover:opacity-80"
+    >
+      {children}
+    </a>
+  );
+}
+
+export function GitStatusBadge({
+  task,
+  compact = true,
+  repoUrl,
+}: GitStatusBadgeProps) {
   // All tasks follow git workflow - show relevant status
 
   // Show PR badge with status (highest priority)
   if (task.pr_number) {
     return (
-      <Badge className="gap-1 text-xs bg-purple-500/10 text-purple-600 dark:text-purple-400">
-        <GitPullRequest className="h-3 w-3" />
-        PR #{task.pr_number}
-      </Badge>
+      <MaybeLink href={task.pr_url ?? pullUrl(repoUrl, task.pr_number)}>
+        <Badge className="gap-1 text-xs bg-purple-500/10 text-purple-600 dark:text-purple-400">
+          <GitPullRequest className="h-3 w-3" />
+          PR #{task.pr_number}
+        </Badge>
+      </MaybeLink>
     );
   }
 
@@ -55,10 +92,12 @@ export function GitStatusBadge({ task, compact = true }: GitStatusBadgeProps) {
   // Show branch badge (when branch exists but no PR yet)
   if (task.branch_name) {
     return (
-      <Badge variant="outline" className="gap-1 text-xs">
-        <GitBranch className="h-3 w-3" />
-        {compact ? "Branch" : task.branch_name}
-      </Badge>
+      <MaybeLink href={branchUrl(repoUrl, task.branch_name)}>
+        <Badge variant="outline" className="gap-1 text-xs">
+          <GitBranch className="h-3 w-3" />
+          {compact ? "Branch" : task.branch_name}
+        </Badge>
+      </MaybeLink>
     );
   }