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, 42 deletions

diff --git a/vendor/rustversion/src/iter.rs b/vendor/rustversion/src/iter.rs
deleted file mode 100644
index 722013c7..00000000
--- a/vendor/rustversion/src/iter.rs
+++ /dev/null
@@ -1,42 +0,0 @@
-use proc_macro::{token_stream, Delimiter, TokenStream, TokenTree};
-
-pub type Iter<'a> = &'a mut IterImpl;
-
-pub struct IterImpl {
-    stack: Vec<token_stream::IntoIter>,
-    peeked: Option<TokenTree>,
-}
-
-pub fn new(tokens: TokenStream) -> IterImpl {
-    IterImpl {
-        stack: vec![tokens.into_iter()],
-        peeked: None,
-    }
-}
-
-impl IterImpl {
-    pub fn peek(&mut self) -> Option<&TokenTree> {
-        self.peeked = self.next();
-        self.peeked.as_ref()
-    }
-}
-
-impl Iterator for IterImpl {
-    type Item = TokenTree;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        if let Some(tt) = self.peeked.take() {
-            return Some(tt);
-        }
-        loop {
-            let top = self.stack.last_mut()?;
-            match top.next() {
-                None => drop(self.stack.pop()),
-                Some(TokenTree::Group(ref group)) if group.delimiter() == Delimiter::None => {
-                    self.stack.push(group.stream().into_iter());
-                }
-                Some(tt) => return Some(tt),
-            }
-        }
-    }
-}