- Introduce a new `webhook` crate to centralize signature validation for GitHub, Hookdeck, and Forgejo webhooks.
- Enable `github-integration` to perform unified webhook signature verification using the `webhook` crate.
- Refactor `github-integration`: replace legacy HMAC verification with the reusable `webhook` structure.
- Extend Podman configuration for Hookdeck webhook signature handling and improve documentation.
- Clean up unused dependencies by migrating to the new implementation.
Signed-off-by: Till Wegmueller <toasterson@gmail.com>
