test(e2e): Playwright smoke test — boot tier always, E2EE composer tier with credentials

Boot tier (runs against vite preview of dist/): login screen renders with
no page or console errors, sw.js is served and registers, the bundled
Element Call mounts in a frame with no failed asset requests. E2EE tier
(skipped without E2E_HOMESERVER/E2E_USER/E2E_PASSWORD): password login,
create an encrypted room, send text, attach a compressed JPEG, and assert
at the network level that every send is m.room.encrypted with no
plaintext body/url/file — the regression test #6/#7/#11 lacked.
Secrets and local usage documented in LOTUS_TESTING.md.

Fixes #90

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

package-lock.json

@@ -81,6 +81,7 @@
       },
       "devDependencies": {
         "@lotusguild/element-call-embedded": "0.25.0-lotus.1",
+        "@playwright/test": "1.63.0",
         "@rollup/plugin-inject": "5.0.5",
         "@rollup/plugin-wasm": "6.2.2",
         "@types/chroma-js": "3.1.2",
@@ -120,7 +121,7 @@
         "vite-plugin-static-copy": "4.1.0"
       },
       "engines": {
-        "node": ">=16.0.0"
+        "node": ">=20.0.0"
       }
     },
     "node_modules/@apideck/better-ajv-errors": {
@@ -2973,6 +2974,22 @@
         "url": "https://github.com/sponsors/Boshen"
       }
     },
+    "node_modules/@playwright/test": {
+      "version": "1.63.0",
+      "resolved": "https://registry.npmjs.org/@playwright/test/-/test-1.63.0.tgz",
+      "integrity": "sha512-oxMK4vllB9RK5NQ2l1pq1IfOf2AvnEuj/vYGDj0H2nMtmtZpKtCwt/l00GEO6xjGfpBNAvjovvYdCm50dRQkpQ==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "playwright": "1.63.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
     "node_modules/@react-types/shared": {
       "version": "3.34.0",
       "resolved": "https://registry.npmjs.org/@react-types/shared/-/shared-3.34.0.tgz",
@@ -10708,6 +10725,35 @@
         "pathe": "^2.0.1"
       }
     },
+    "node_modules/playwright": {
+      "version": "1.63.0",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.63.0.tgz",
+      "integrity": "sha512-+7ziBLidS4NaNCdt57SUDT+wYmmd5fmiQejUic/kb+YsYSCPyOOE9sebzMjNmQrsnNpDJqd4WHvV/8lfKfUDUg==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "playwright-core": "1.63.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
+    "node_modules/playwright-core": {
+      "version": "1.63.0",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.63.0.tgz",
+      "integrity": "sha512-rYCsBF/M5HjUch52bbtVONEFjv6Xu8sm8h72dNlR5bzIE1fvC/bxgspzkjSfU+MweEMmPM8KJebG6nnyxo5mCg==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "playwright-core": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
     "node_modules/pngjs": {
       "version": "5.0.0",
       "resolved": "https://registry.npmjs.org/pngjs/-/pngjs-5.0.0.tgz",