feat(ui): add agent creation choice modal and full-page config

Replace the direct agent config dialog with a choice modal offering two
paths: "Ask the CEO to create a new agent" (opens pre-filled issue) or
"I want advanced configuration myself" (navigates to /agents/new).

- Extend NewIssueDefaults with title/description for pre-fill support
- Add /agents/new route with full-page agent configuration form
- NewAgentDialog now shows CEO recommendation modal

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

ui/src/components/NewIssueDialog.tsx

@@ -332,7 +332,18 @@ export function NewIssueDialog() {
     setDialogCompanyId(selectedCompanyId);
 
     const draft = loadDraft();
-    if (draft && draft.title.trim()) {
+    if (newIssueDefaults.title) {
+      setTitle(newIssueDefaults.title);
+      setDescription(newIssueDefaults.description ?? "");
+      setStatus(newIssueDefaults.status ?? "todo");
+      setPriority(newIssueDefaults.priority ?? "");
+      setProjectId(newIssueDefaults.projectId ?? "");
+      setAssigneeId(newIssueDefaults.assigneeAgentId ?? "");
+      setAssigneeModelOverride("");
+      setAssigneeThinkingEffort("");
+      setAssigneeChrome(false);
+      setAssigneeUseProjectWorkspace(true);
+    } else if (draft && draft.title.trim()) {
       setTitle(draft.title);
       setDescription(draft.description);
       setStatus(draft.status || "todo");