feat: migrate from Cedar to SpiceDB authorization system

This is a major architectural change that replaces the Cedar policy-based
authorization system with SpiceDB's relation-based authorization.

Key changes:

- Migrate from Rust to Go implementation
- Replace Cedar policies with SpiceDB schema and relationships
- Switch from envoy `ext_authz` with Cedar to SpiceDB permission checks
- Update build system and dependencies for Go ecosystem
- Maintain Envoy integration for external authorization

This change enables more flexible permission modeling through SpiceDB's
Google Zanzibar inspired relation-based system, supporting complex
hierarchical permissions that were difficult to express in Cedar.

Breaking change: Existing Cedar policies and Rust-based configuration
will no longer work and need to be migrated to SpiceDB schema.

1 files changed, 0 insertions, 17 deletions

diff --git a/vendor/http/src/convert.rs b/vendor/http/src/convert.rs
deleted file mode 100644
index 682e0ed5..00000000
--- a/vendor/http/src/convert.rs
+++ /dev/null
@@ -1,17 +0,0 @@
-macro_rules! if_downcast_into {
-    ($in_ty:ty, $out_ty:ty, $val:ident, $body:expr) => {{
-        if std::any::TypeId::of::<$in_ty>() == std::any::TypeId::of::<$out_ty>() {
-            // Store the value in an `Option` so we can `take`
-            // it after casting to `&mut dyn Any`.
-            let mut slot = Some($val);
-            // Re-write the `$val` ident with the downcasted value.
-            let $val = (&mut slot as &mut dyn std::any::Any)
-                .downcast_mut::<Option<$out_ty>>()
-                .unwrap()
-                .take()
-                .unwrap();
-            // Run the $body in scope of the replaced val.
-            $body
-        }
-    }};
-}