feat(tests): add TypeScript client integration test support (#4185)

Integration tests can now validate the TypeScript SDK alongside Python
tests when running against server-mode stacks. Currently, this only adds
a _small_ number of tests. We should extend only if truly needed -- this
smoke check may be sufficient.

When `RUN_CLIENT_TS_TESTS=1` is set, the test script runs TypeScript
tests after Python tests pass. Tests are mapped via
`tests/integration/client-typescript/suites.json` which defines which
TypeScript test files correspond to each Python suite/setup combination.

The fact that we need exact "test_id"s (which are actually generated by
pytest) to be hardcoded inside the Typescript tests (so we hit the
recorded paths) is a big smell and it might become grating, but maybe
the benefit is worth it if we keep this test suite _small_ and targeted.

## Test Plan

Run with TypeScript tests enabled:
```bash
OPENAI_API_KEY=dummy RUN_CLIENT_TS_TESTS=1 \
  scripts/integration-tests.sh --stack-config server:ci-tests --suite responses --setup gpt
```

.github/actions/setup-typescript-client/action.yml

@@ -0,0 +1,35 @@
+name: Setup TypeScript client
+description: Conditionally checkout and link llama-stack-client-typescript based on client-version
+inputs:
+  client-version:
+    description: 'Client version (latest or published)'
+    required: true
+
+outputs:
+  ts-client-path:
+    description: 'Path or version to use for TypeScript client'
+    value: ${{ steps.set-path.outputs.ts-client-path }}
+
+runs:
+  using: "composite"
+  steps:
+    - name: Checkout TypeScript client (latest)
+      if: ${{ inputs.client-version == 'latest' }}
+      uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      with:
+        repository: llamastack/llama-stack-client-typescript
+        ref: main
+        path: .ts-client-checkout
+
+    - name: Set TS_CLIENT_PATH
+      id: set-path
+      shell: bash
+      run: |
+        if [ "${{ inputs.client-version }}" = "latest" ]; then
+          echo "ts-client-path=${{ github.workspace }}/.ts-client-checkout" >> $GITHUB_OUTPUT
+        elif [ "${{ inputs.client-version }}" = "published" ]; then
+          echo "ts-client-path=^0.3.2" >> $GITHUB_OUTPUT
+        else
+          echo "::error::Invalid client-version: ${{ inputs.client-version }}"
+          exit 1
+        fi