ci(claude): centralize claude.yml via reusable workflow

[inference-gateway-maintainer]

Summary

Centralized-config changes in one PR:

1. Adds/updates .github/workflows/claude.yml as a thin caller of the org reusable workflow
   inference-gateway/.github/.github/workflows/claude.yml@main,
   wiring the @claude bot (anthropics/claude-code-action) into this repo.
2. Bumps this repo's Flox claude-code pin (.flox/env/manifest.toml) to
   2.1.201 (the latest flox catalog version) and
   refreshes .flox/env/manifest.lock.

Setup lives centrally, so future moves (action bump, model, tool scope, CLI version) are a
re-run of migrate-claude.yml instead of a hand-edit per repo.

Ran in CI:

• sed the claude-code.version floor in .flox/env/manifest.toml to the latest catalog version
• flox upgrade claude-code + flox activate to refresh .flox/env/manifest.lock in canonical form

Note: claude-code is a flox catalog package (nixpkgs mirror), not a GitHub release,
so the latest version is read from flox show claude-code. No .claude/ config is
regenerated (claude-code has no init step).

Notes

• Tools = a shared default (Bash(task:*),Bash(gh:*),Bash(git:*)) + the language preset +
  this repo's extras, configured in repos.yaml (the entry's orchestrators.claude block).
• If this repo previously narrowed gh scope or used a quirky tool list, that is preserved
  via allowed-tools; otherwise the list is normalized (e.g. a stray Bash(go:*) on a
  non-Go repo is dropped).

Filed by migrate-claude.yml.