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, 16 deletions

diff --git a/vendor/syn/src/print.rs b/vendor/syn/src/print.rs
deleted file mode 100644
index 07409932..00000000
--- a/vendor/syn/src/print.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-use proc_macro2::TokenStream;
-use quote::ToTokens;
-
-pub(crate) struct TokensOrDefault<'a, T: 'a>(pub &'a Option<T>);
-
-impl<'a, T> ToTokens for TokensOrDefault<'a, T>
-where
-    T: ToTokens + Default,
-{
-    fn to_tokens(&self, tokens: &mut TokenStream) {
-        match self.0 {
-            Some(t) => t.to_tokens(tokens),
-            None => T::default().to_tokens(tokens),
-        }
-    }
-}