ci: Run SDK browser smoke tests as a separate workflow job (#3372)

## Summary

Separates SDK browser smoke tests from the main browser end-to-end test
job into its own dedicated workflow job for better CI visibility and
parallel execution.

## Changes

- Extracted `npm run test-browser-smoke` from existing browser test job
- Created new `sdk-browser-smoke-test` job with required Docker services
and test environment configuration – this includes `cassandra` now for
the resend testing.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Separates SDK browser smoke tests from the main browser E2E job and
updates test credentials.
> 
> - Adds `sdk-browser-smoke-test` job in
`.github/workflows/validate.yml` with browser setup, required Docker
services (including `cassandra`), and runs `npm run test-browser-smoke`
> - Removes inline `npm run test-browser-smoke` execution from
`sdk-browser-e2e` job
> - Updates `packages/sdk/test/browser-smoke-test/smoke-test.html` to
use a new `PUBLISHER_KEY` value
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
9562af2. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: mondoreale

.github/workflows/validate.yml

@@ -155,7 +155,17 @@ jobs:
       command: |
         sudo apt-get install xvfb
         xvfb-run --auto-servernum npm run test-browser-end-to-end
-        npm run test-browser-smoke
+  sdk-browser-smoke-test:
+    needs: build
+    uses: ./.github/workflows/test-setup.yml
+    with:
+      package: sdk
+      browser: true
+      extra-log-prefix: '-browser-smoke-test'
+      docker-services: cassandra init-keyspace dev-chain-fast deploy-network-subgraphs-fastchain
+      run-entry-point: true
+      run-nodes: true
+      command: npm run test-browser-smoke
   cli-tools:
     needs: build
     uses: ./.github/workflows/test-setup.yml

packages/sdk/test/browser-smoke-test/smoke-test.html

@@ -6,7 +6,7 @@
     <script src='/static/exports-umd.min.js'></script>
     <script>
         const SUBSCRIBER_KEY = '0000000000000000000000000000000000000000000000000000000000000055'
-        const PUBLISHER_KEY = '0000000000000000000000000000000000000000000000000000000000000056'
+        const PUBLISHER_KEY = '0x5e98cce00cff5dea6b454889f359a4ec06b9fa6b88e9d69b86de8e1c81887da0'
         const STORAGE_NODE_ADDRESS = '0xde1112f631486CfC759A50196853011528bC5FA0'
         const PUBLISH_RATE_IN_MS = 300
         let publishMsgCounter = 0