feat(cli): TUI grid threshold, narrow agents view, new-task popup, browser launch

- Lower the multi-panel grid threshold from 100×24 to 80×20 so standard
  terminals render the full layout instead of falling back to single-pane.
- Agents view stacks list above detail when cols < 80; Tab focus model
  preserved.
- Board view: press [n] to open a centered create-task popup. Title is
  edited via ink-text-input; submit calls TaskStore.createTask, refresh
  the task list on success.
- System panel: shows the tokenized auth URL alongside the token, says
  "no auth" plainly when --no-auth was used, and prompts with
  "Press [Enter] to open in browser". Enter (while System is focused)
  spawns the platform's URL opener (open / start / xdg-open).
- Tighten log-row layout: each row is now a single Text with inline
  spans + fixed-width prefix slot so columns align and the highlight
  bar spans the full row.
- Default status section is "logs" so the live feed is what users see
  when they run `fn`.
- Drop the ASCII circle brand mark from the splash; FUSION block
  letters + tagline + spinner only, pinned to the top-left.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/cli/src/commands/dashboard-tui/__tests__/app.test.tsx

@@ -45,6 +45,12 @@ function makeInteractiveData(opts: {
   return {
     listProjects: async () => projects,
     listTasks: async () => tasks,
+    createTask: async (_path: string, input: { title: string; description?: string }) => ({
+      id: "new",
+      title: input.title,
+      description: input.description ?? input.title,
+      column: "todo",
+    }) as TaskItem,
     listAgents: async () => agents,
     getAgentDetail: async (_id: string) => detail,
     updateAgentState: async (_id: string, _state: string) => {},