chore(client): scope a tsconfig to e2e/ so the SDK harness typechecks cleanly

The e2e harness files (broker.ts/run.ts/sdk-entry.ts) live outside the client
tsconfig include (src/test), so an editor's broad tsc flagged process/node:*/
playwright as unresolved. Add packages/client/e2e/tsconfig.json (extends base,
types: bun) — tsc -p e2e is exit 0; the client tsconfig stays unchanged/clean.
Drop an unused getCurrentUser import in sdk-entry.ts.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/client/e2e/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "../../../tsconfig.base.json",
+  "compilerOptions": {
+    "types": ["bun"],
+    "noEmit": true
+  },
+  "include": ["."]
+}