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/App.tsx

@@ -24,6 +24,7 @@ import { Inbox } from "./pages/Inbox";
 import { CompanySettings } from "./pages/CompanySettings";
 import { DesignGuide } from "./pages/DesignGuide";
 import { OrgChart } from "./pages/OrgChart";
+import { NewAgent } from "./pages/NewAgent";
 import { AuthPage } from "./pages/Auth";
 import { BoardClaimPage } from "./pages/BoardClaim";
 import { InviteLandingPage } from "./pages/InviteLanding";
@@ -101,6 +102,7 @@ function boardRoutes() {
       <Route path="agents/active" element={<Agents />} />
       <Route path="agents/paused" element={<Agents />} />
       <Route path="agents/error" element={<Agents />} />
+      <Route path="agents/new" element={<NewAgent />} />
       <Route path="agents/:agentId" element={<AgentDetail />} />
       <Route path="agents/:agentId/:tab" element={<AgentDetail />} />
       <Route path="agents/:agentId/runs/:runId" element={<AgentDetail />} />
@@ -214,6 +216,7 @@ export function App() {
           <Route path="issues" element={<UnprefixedBoardRedirect />} />
           <Route path="issues/:issueId" element={<UnprefixedBoardRedirect />} />
           <Route path="agents" element={<UnprefixedBoardRedirect />} />
+          <Route path="agents/new" element={<UnprefixedBoardRedirect />} />
           <Route path="agents/:agentId" element={<UnprefixedBoardRedirect />} />
           <Route path="agents/:agentId/:tab" element={<UnprefixedBoardRedirect />} />
           <Route path="agents/:agentId/runs/:runId" element={<UnprefixedBoardRedirect />} />