* test(e2e): verify Claude is prefilled with issue URL on start
Regression test for #6613: when starting a workspace from a newly
created GitHub issue, ensure the issue URL is passed to Claude via
`--prefill` and `--dangerously-skip-permissions` flags. This prevents
context loss after issue creation.
* test(e2e): fix GitHub-issue-start prefill test flakiness
- Reorder mock API handlers to ensure `/labels` and `/assignees` paths match before the specific issue endpoint
- Replace regex heading matcher with exact string for more reliable assertions
- Refactor terminal content polling to capture text once and reuse in subsequent assertions
