test(e2e): smoke test verifying v0.2 inbox empty state

Task 32 of the slice plan. playwright.config.ts (testDir
tests/e2e, single worker, 60s default timeout, list reporter)
and a smoke spec that launches the built main bundle, waits
for the inbox renderer, and asserts the v0.2 empty-state copy
'첫 기억을 구출해보세요.' is rendered.

Build verified end-to-end (`npm run build` exits 0, produces
out/main/index.js + out/preload/index.mjs + the inbox /
quickcapture renderer chunks). Playwright's chromium bundle
installed.

Known issue (deferred to a follow-up debug session): on this
specific Windows machine, electron@41.3.0's main-process
module hook is not injecting the real `electron` API into the
launched bundle. `require('electron')` from the entry script
returns the on-disk path string (the package's index.js
default), and `process.electronBinding` / `process.type` are
undefined inside the spawned process. This reproduces with a
minimal package.json + main.js outside this repo — i.e. it's
not a slice bug. The smoke test currently fails with
'Process failed to launch!' at the
`app.whenReady().then(...)` line because `app` is undefined.

When the host issue is sorted, no test changes should be
required: build, config, and spec are correct. Likely fixes:
clean-reinstall electron + node-modules, try electron@latest,
or invoke through `npx electron` rather than the binary
directly. Captured in project_inkling_status memory under
'open issues'.

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

playwright.config.ts

@@ -0,0 +1,8 @@
+import { defineConfig } from '@playwright/test';
+export default defineConfig({
+  testDir: './tests/e2e',
+  timeout: 60_000,
+  retries: 0,
+  workers: 1,
+  reporter: 'list'
+});