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, 63 deletions

diff --git a/vendor/syn/src/span.rs b/vendor/syn/src/span.rs
deleted file mode 100644
index eb277947..00000000
--- a/vendor/syn/src/span.rs
+++ /dev/null
@@ -1,63 +0,0 @@
-use proc_macro2::extra::DelimSpan;
-use proc_macro2::{Delimiter, Group, Span, TokenStream};
-
-#[doc(hidden)]
-pub trait IntoSpans<S> {
-    fn into_spans(self) -> S;
-}
-
-impl IntoSpans<Span> for Span {
-    fn into_spans(self) -> Span {
-        self
-    }
-}
-
-impl IntoSpans<[Span; 1]> for Span {
-    fn into_spans(self) -> [Span; 1] {
-        [self]
-    }
-}
-
-impl IntoSpans<[Span; 2]> for Span {
-    fn into_spans(self) -> [Span; 2] {
-        [self, self]
-    }
-}
-
-impl IntoSpans<[Span; 3]> for Span {
-    fn into_spans(self) -> [Span; 3] {
-        [self, self, self]
-    }
-}
-
-impl IntoSpans<[Span; 1]> for [Span; 1] {
-    fn into_spans(self) -> [Span; 1] {
-        self
-    }
-}
-
-impl IntoSpans<[Span; 2]> for [Span; 2] {
-    fn into_spans(self) -> [Span; 2] {
-        self
-    }
-}
-
-impl IntoSpans<[Span; 3]> for [Span; 3] {
-    fn into_spans(self) -> [Span; 3] {
-        self
-    }
-}
-
-impl IntoSpans<DelimSpan> for Span {
-    fn into_spans(self) -> DelimSpan {
-        let mut group = Group::new(Delimiter::None, TokenStream::new());
-        group.set_span(self);
-        group.delim_span()
-    }
-}
-
-impl IntoSpans<DelimSpan> for DelimSpan {
-    fn into_spans(self) -> DelimSpan {
-        self
-    }
-}