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, 59 deletions

diff --git a/vendor/hex/src/error.rs b/vendor/hex/src/error.rs
deleted file mode 100644
index ff7a3b5c..00000000
--- a/vendor/hex/src/error.rs
+++ /dev/null
@@ -1,59 +0,0 @@
-use core::fmt;
-
-/// The error type for decoding a hex string into `Vec<u8>` or `[u8; N]`.
-#[derive(Debug, Clone, Copy, PartialEq)]
-pub enum FromHexError {
-    /// An invalid character was found. Valid ones are: `0...9`, `a...f`
-    /// or `A...F`.
-    InvalidHexCharacter { c: char, index: usize },
-
-    /// A hex string's length needs to be even, as two digits correspond to
-    /// one byte.
-    OddLength,
-
-    /// If the hex string is decoded into a fixed sized container, such as an
-    /// array, the hex string's length * 2 has to match the container's
-    /// length.
-    InvalidStringLength,
-}
-
-#[cfg(feature = "std")]
-impl std::error::Error for FromHexError {}
-
-impl fmt::Display for FromHexError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match *self {
-            FromHexError::InvalidHexCharacter { c, index } => {
-                write!(f, "Invalid character {:?} at position {}", c, index)
-            }
-            FromHexError::OddLength => write!(f, "Odd number of digits"),
-            FromHexError::InvalidStringLength => write!(f, "Invalid string length"),
-        }
-    }
-}
-
-#[cfg(test)]
-// this feature flag is here to suppress unused
-// warnings of `super::*` and `pretty_assertions::assert_eq`
-#[cfg(feature = "alloc")]
-mod tests {
-    use super::*;
-    #[cfg(feature = "alloc")]
-    use alloc::string::ToString;
-    use pretty_assertions::assert_eq;
-
-    #[test]
-    #[cfg(feature = "alloc")]
-    fn test_display() {
-        assert_eq!(
-            FromHexError::InvalidHexCharacter { c: '\n', index: 5 }.to_string(),
-            "Invalid character '\\n' at position 5"
-        );
-
-        assert_eq!(FromHexError::OddLength.to_string(), "Odd number of digits");
-        assert_eq!(
-            FromHexError::InvalidStringLength.to_string(),
-            "Invalid string length"
-        );
-    }
-}