feat: #58 Tests E2E Playwright — 44 tests desktop + CI

- playwright.config.ts: chromium-desktop + chromium-mobile
- tests/e2e/obsigate.spec.ts: 44 tests en 11 sections
  - Dashboard & Navigation (8 tests)
  - Full-Text Search (10 tests)
  - File Navigation & Viewer (5 tests)
  - Editor (4 tests: Forge, basic modal, Ctrl+S)
  - Mermaid Diagrams (2 tests)
  - PDF Export, Dark Mode, Responsive, Saved Searches
  - Keyboard Shortcuts (Ctrl+K, /, Escape)
  - Context Menu directory
- CI: nouveau job e2e dans .gitea/workflows/ci.yml
- ROADMAP: #58 marque FAIT
- .gitignore: node_modules, test-results, playwright-report

playwright.config.ts

@@ -0,0 +1,31 @@
+import { defineConfig, devices } from '@playwright/test';
+
+export default defineConfig({
+  testDir: './tests/e2e',
+  fullyParallel: false,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 1 : 0,
+  workers: 1,
+  reporter: process.env.CI ? 'github' : 'list',
+  timeout: 60000,
+  expect: { timeout: 10000 },
+
+  use: {
+    baseURL: process.env.BASE_URL || 'http://localhost:2020',
+    trace: 'on-first-retry',
+    screenshot: 'only-on-failure',
+  },
+
+  projects: [
+    {
+      name: 'chromium-desktop',
+      use: { ...devices['Desktop Chrome'] },
+    },
+    {
+      name: 'chromium-mobile',
+      use: { ...devices['Pixel 5'] },
+    },
+  ],
+
+  webServer: process.env.CI ? [] : [],
+});