Phase 9: homebrew content + packs

- Homebrew entity (monster/spell/item/feat/condition) — Dexie v6, repo, hook,
  cascade-deleted with campaign
- Homebrew editor page: per-kind fields + description, create/edit/delete
- Compendium merges campaign homebrew of the matching kind (HB badge, generic
  HomebrewDetail) with the same cross-links (add monster->combat, spell/item->character)
- Content packs: export/import homebrew as JSON (validated, ids reassigned)
- System extensibility documented via the existing RulesSystem registry seam
- Fix: card editors (homebrew/npc/quest/note) debounce-save the FULL snapshot, not
  partial patches — editing two fields fast no longer drops an edit

New homebrew e2e + cascade test coverage.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

e2e/homebrew.spec.ts

@@ -0,0 +1,31 @@
+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();
+});
+
+test('homebrew: create a custom monster and find it in the compendium', async ({ page }) => {
+  await page.getByRole('button', { name: '+ New campaign' }).first().click();
+  await page.locator('input[data-autofocus]').fill('Brew');
+  await page.getByRole('button', { name: 'Create' }).click();
+  await page.getByRole('link', { name: 'Dashboard' }).click();
+  await page.getByRole('link', { name: 'Homebrew' }).click();
+
+  // Create a homebrew monster and name it
+  await page.getByRole('button', { name: /New monster/ }).click();
+  const nameInput = page.getByLabel('Homebrew name');
+  await nameInput.fill('Dire Frog');
+  await page.getByLabel('Hit Points').fill('22');
+
+  // It shows up in the compendium bestiary with an HB badge
+  await page.getByRole('link', { name: 'Compendium' }).click();
+  await page.getByPlaceholder(/Search bestiary/i).fill('Dire Frog');
+  await page.getByRole('button', { name: /Dire Frog/ }).first().click();
+  await expect(page.getByText(/Homebrew monster/)).toBeVisible();
+  await expect(page.getByText('HB').first()).toBeVisible();
+});