activity-sport-type: e2e test + register spec in playwright config

- e2e/activity-sport-type.test.ts: register → create activity with a sport →
  assert the sport badge renders on the detail page. Passes locally against an
  E2E=true server.
- playwright.config.ts: add the `activity-sport-type` project so the spec
  actually runs (specs only execute if a project testMatch matches them).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

playwright.config.ts

@@ -114,6 +114,14 @@ export default defineConfig({
         baseURL: "http://localhost:3000",
       },
     },
+    {
+      name: "activity-sport-type",
+      testMatch: "activity-sport-type.test.ts",
+      use: {
+        ...devices["Desktop Chrome"],
+        baseURL: "http://localhost:3000",
+      },
+    },
   ],
   webServer: process.env.CI
     ? [