[BUG] Duplicate `runner.run(Component)` in Twisted pubsub basic example

[oberstet]

Problem

examples/twisted/wamp/pubsub/basic/frontend.py calls runner.run(Component) twice in a row:

runner = ApplicationRunner(url, realm, extra)
runner.run(Component)
runner.run(Component)   # duplicate

(lines 68-69). The second call is dead/duplicate code — ApplicationRunner.run()
starts and blocks on the reactor, so the second call is at best redundant and at
worst confusing for readers learning from the example.

Fix

Remove the duplicate second runner.run(Component) line so the example ends with
a single runner.run(Component).

Notes

• Examples-only change; no library code or tests affected.
• A community PR already implements this fix: Remove duplicate run call for ApplicationRunner #1887 (thanks @JavierSab). This
  issue is filed so that PR has an originating issue to reference
  (Closes #<this-issue>), per our issue-first workflow.

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This analysis was produced with AI assistance (Claude Code) and requires human review before filing. Which I did.

Checklist

• I have searched existing issues to avoid duplicates
• I have provided a minimal reproducible example
• I have included version information
• I have included error messages/logs

[oberstet]

fixed via #1887