chore(cassettes): Add a script to automate cassettes renewal

[timothedelion]

Add a script ~/ggmcp/scripts/update-cassettes.sh to automate cassettes renewal :

1. Preflight — checks gh and uv are available, ensures clean working tree
2. Branch setup — checks out a fresh chore/update-vcr-cassettes branch from the base branch
3. Record — runs make update-cassettes with up to 3 attempts (2 retries), 60s delay between retries (same pattern as
   tokenscanner's nightly)
4. Commit & push — only if cassettes actually changed; uses --force-with-lease so the same branch can be reused
5. PR — creates a new PR via gh pr create, or prints the existing one if the branch already has an open PR

Usage: cd ~/ggmcp && ./scripts/update-cassettes.sh

See the result : #129

Issue: APPAI-481

[linear]

APPAI-481 MCP server : Add a pipeline in the CI to renew the API KEY and the cassettes