D6: AI Director polish + parity hardening

- pf2e parity: a unit test confirms the director carries the system through
  (systemConstraint + prompt say Pathfinder 2e, no cross-system leak) and still
  produces a grounded deterministic turn. (Degree-of-success/conditions already
  branch per system via the shared kernel.)
- UX: the transcript pane is now a bounded, scrollable region (max-h-[60vh]) so
  long sessions don't blow the page layout; it still auto-scrolls to the newest line.
- e2e: e2e/director.spec.ts exercises the full flow against a real browser — DM
  narrates a grounded scene with no API key (deterministic badge, empty-state
  clears, Continue appears), and the player persona seats a party character and
  takes a turn.

396 unit tests + 2 director e2e green; lint clean; build OK.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

e2e/director.spec.ts

@@ -0,0 +1,44 @@
+import { test, expect } from '@playwright/test';
+
+test.beforeEach(async ({ page }) => {
+  await page.goto('/');
+  await page.evaluate(async () => {
+    indexedDB.deleteDatabase('ttrpg-manager');
+    localStorage.clear();
+  });
+  await page.reload();
+  // Load the sample campaign (gives us a party + an active encounter).
+  await page.getByLabel('Settings').click();
+  await page.getByRole('button', { name: 'Load sample campaign' }).click();
+  await expect(page.getByRole('heading', { name: 'Sample: Lost Mine' })).toBeVisible();
+});
+
+test('AI Director narrates a grounded scene with no API key (deterministic)', async ({ page }) => {
+  await page.getByLabel('Primary').getByRole('link', { name: 'AI Director' }).click();
+  await expect(page.getByRole('heading', { name: 'AI Director' })).toBeVisible();
+  await expect(page.getByText(/deterministic mode/)).toBeVisible();
+
+  // Empty until we start.
+  await expect(page.getByText('The story begins when you start the scene.')).toBeVisible();
+
+  await page.getByRole('button', { name: 'Begin the scene' }).click();
+
+  // A narration entry appears; the empty-state is gone; source badge shows deterministic.
+  await expect(page.getByText('The story begins when you start the scene.')).toBeHidden();
+  await expect(page.getByText('deterministic', { exact: true })).toBeVisible();
+  await expect(page.getByRole('button', { name: 'Continue' })).toBeVisible();
+});
+
+test('the director can play a chosen party character (player persona)', async ({ page }) => {
+  await page.getByLabel('Primary').getByRole('link', { name: 'AI Director' }).click();
+
+  await page.getByRole('button', { name: 'Player', exact: true }).click();
+  // Subtitle reflects the mode.
+  await expect(page.getByText(/· Player/)).toBeVisible();
+
+  // Seat the AI on the first party character.
+  await page.getByLabel('Character the AI plays').selectOption({ index: 1 });
+
+  await page.getByRole('button', { name: /Take the first action|Take turn/ }).click();
+  await expect(page.getByText('deterministic', { exact: true })).toBeVisible();
+});