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, 41 deletions

diff --git a/vendor/writeable/src/either.rs b/vendor/writeable/src/either.rs
deleted file mode 100644
index 67be94f5..00000000
--- a/vendor/writeable/src/either.rs
+++ /dev/null
@@ -1,41 +0,0 @@
-// This file is part of ICU4X. For terms of use, please see the file
-// called LICENSE at the top level of the ICU4X source tree
-// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
-
-use crate::*;
-use ::either::Either;
-
-/// A [`Writeable`] impl that delegates to one type or another type.
-impl<W0, W1> Writeable for Either<W0, W1>
-where
-    W0: Writeable,
-    W1: Writeable,
-{
-    fn write_to<W: fmt::Write + ?Sized>(&self, sink: &mut W) -> fmt::Result {
-        match self {
-            Either::Left(w) => w.write_to(sink),
-            Either::Right(w) => w.write_to(sink),
-        }
-    }
-
-    fn write_to_parts<S: PartsWrite + ?Sized>(&self, sink: &mut S) -> fmt::Result {
-        match self {
-            Either::Left(w) => w.write_to_parts(sink),
-            Either::Right(w) => w.write_to_parts(sink),
-        }
-    }
-
-    fn writeable_length_hint(&self) -> LengthHint {
-        match self {
-            Either::Left(w) => w.writeable_length_hint(),
-            Either::Right(w) => w.writeable_length_hint(),
-        }
-    }
-
-    fn write_to_string(&self) -> Cow<str> {
-        match self {
-            Either::Left(w) => w.write_to_string(),
-            Either::Right(w) => w.write_to_string(),
-        }
-    }
-}