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, 61 deletions

diff --git a/vendor/writeable/examples/writeable_message.rs b/vendor/writeable/examples/writeable_message.rs
deleted file mode 100644
index ca7c773d..00000000
--- a/vendor/writeable/examples/writeable_message.rs
+++ /dev/null
@@ -1,61 +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 ).
-
-// This example illustrates a very simple type implementing Writeable.
-
-#![no_main] // https://github.com/unicode-org/icu4x/issues/395
-icu_benchmark_macros::instrument!();
-
-use std::fmt;
-use writeable::*;
-
-struct WriteableMessage<W: Writeable>(W);
-
-const GREETING: Part = Part {
-    category: "meaning",
-    value: "greeting",
-};
-
-const EMOJI: Part = Part {
-    category: "meaning",
-    value: "emoji",
-};
-
-impl<V: Writeable> Writeable for WriteableMessage<V> {
-    fn write_to_parts<W: PartsWrite + ?Sized>(&self, sink: &mut W) -> fmt::Result {
-        use fmt::Write;
-        sink.with_part(GREETING, |g| {
-            g.write_str("Hello")?;
-            g.write_str(" ")?;
-            self.0.write_to(g)
-        })?;
-        sink.write_char(' ')?;
-        sink.with_part(EMOJI, |e| e.write_char('😅'))
-    }
-
-    fn writeable_length_hint(&self) -> LengthHint {
-        LengthHint::exact(11) + self.0.writeable_length_hint()
-    }
-}
-
-impl<V: Writeable> fmt::Display for WriteableMessage<V> {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.write_to(f)
-    }
-}
-
-fn main() {
-    let (string, parts) =
-        writeable::_internal::writeable_to_parts_for_test(&WriteableMessage("world"));
-
-    assert_eq!(string, "Hello world 😅");
-
-    // Print the greeting only
-    let (start, end, _) = parts
-        .into_iter()
-        .find(|(_, _, part)| part == &GREETING)
-        .unwrap();
-    println!("{}", &string[start..end]);
-}