feat: add external authorization service (authzd) with JWT authentication

- Add new authzd gRPC service implementing Envoy's external authorization API
- Integrate JWT authentication filter in Envoy configuration with claim extraction
- Update middleware to support both cookie-based and header-based user authentication
- Add comprehensive test coverage for authorization service and server
- Configure proper service orchestration with authzd, sparkled, and Envoy
- Update build system and Docker configuration for multi-service deployment
- Add grpcurl tool for gRPC service debugging and testing

This enables fine-grained authorization control through Envoy's ext_authz filter
while maintaining backward compatibility with existing cookie-based authentication.

1 files changed, 32 insertions, 0 deletions

diff --git a/vendor/cel.dev/expr/CONTRIBUTING.md b/vendor/cel.dev/expr/CONTRIBUTING.md
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+# How to Contribute
+
+We'd love to accept your patches and contributions to this project. There are a
+few guidelines you need to follow.
+
+## Contributor License Agreement
+
+Contributions to this project must be accompanied by a Contributor License
+Agreement. You (or your employer) retain the copyright to your contribution,
+this simply gives us permission to use and redistribute your contributions as
+part of the project. Head over to <https://cla.developers.google.com/> to see
+your current agreements on file or to sign a new one.
+
+You generally only need to submit a CLA once, so if you've already submitted one
+(even if it was for a different project), you probably don't need to do it
+again.
+
+## Code reviews
+
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.
+
+## What to expect from maintainers
+
+Expect maintainers to respond to new issues or pull requests within a week.
+For outstanding and ongoing issues and particularly for long-running
+pull requests, expect the maintainers to review within a week of a
+contributor asking for a new review. There is no commitment to resolution --
+merging or closing a pull request, or fixing or closing an issue -- because some
+issues will require more discussion than others.