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, 32 deletions

diff --git a/vendor/itertools/src/group_map.rs b/vendor/itertools/src/group_map.rs
deleted file mode 100644
index 3dcee83a..00000000
--- a/vendor/itertools/src/group_map.rs
+++ /dev/null
@@ -1,32 +0,0 @@
-#![cfg(feature = "use_std")]
-
-use std::collections::HashMap;
-use std::hash::Hash;
-use std::iter::Iterator;
-
-/// Return a `HashMap` of keys mapped to a list of their corresponding values.
-///
-/// See [`.into_group_map()`](crate::Itertools::into_group_map)
-/// for more information.
-pub fn into_group_map<I, K, V>(iter: I) -> HashMap<K, Vec<V>>
-where
-    I: Iterator<Item = (K, V)>,
-    K: Hash + Eq,
-{
-    let mut lookup = HashMap::new();
-
-    iter.for_each(|(key, val)| {
-        lookup.entry(key).or_insert_with(Vec::new).push(val);
-    });
-
-    lookup
-}
-
-pub fn into_group_map_by<I, K, V, F>(iter: I, mut f: F) -> HashMap<K, Vec<V>>
-where
-    I: Iterator<Item = V>,
-    K: Hash + Eq,
-    F: FnMut(&V) -> K,
-{
-    into_group_map(iter.map(|v| (f(&v), v)))
-}