e2e: pin Playwright to 1.59.1

`@playwright/test` was loose-pinned to ^1.50.0; npm resolved it
to 1.59.1 inside the runner image, which only ships browser
binaries for 1.50.0. Pin both the package and the docker image
to v1.59.1 so deps and binaries stay aligned.

e2e/Dockerfile.playwright

@@ -6,7 +6,7 @@
 # because the workflow steps execute inside a runner container,
 # not on the host where compose publishes its ports.
 
-FROM mcr.microsoft.com/playwright:v1.50.0-jammy
+FROM mcr.microsoft.com/playwright:v1.59.1-jammy
 
 WORKDIR /work
 

e2e/playwright/package.json

@@ -9,6 +9,6 @@
     "test:debug": "PWDEBUG=1 playwright test"
   },
   "devDependencies": {
-    "@playwright/test": "^1.50.0"
+    "@playwright/test": "1.59.1"
   }
 }