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.

2 files changed, 0 insertions, 42 deletions

diff --git a/vendor/same-file/examples/is_same_file.rs b/vendor/same-file/examples/is_same_file.rs
deleted file mode 100644
index 6ba948a4..00000000
--- a/vendor/same-file/examples/is_same_file.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-use same_file::is_same_file;
-use std::io;
-
-fn try_main() -> Result<(), io::Error> {
-    assert!(is_same_file("/bin/sh", "/usr/bin/sh")?);
-    Ok(())
-}
-
-fn main() {
-    try_main().unwrap();
-}
diff --git a/vendor/same-file/examples/is_stderr.rs b/vendor/same-file/examples/is_stderr.rs
deleted file mode 100644
index 1078695d..00000000
--- a/vendor/same-file/examples/is_stderr.rs
+++ /dev/null
@@ -1,31 +0,0 @@
-use std::io;
-use std::process;
-
-use same_file::Handle;
-
-fn main() {
-    if let Err(err) = run() {
-        println!("{}", err);
-        process::exit(1);
-    }
-}
-
-fn run() -> io::Result<()> {
-    // Run with `cargo run --example is_stderr 2> examples/stderr` to see
-    // interesting output.
-    let candidates = &[
-        "examples/is_same_file.rs",
-        "examples/is_stderr.rs",
-        "examples/stderr",
-    ];
-    let stderr_handle = Handle::stderr()?;
-    for candidate in candidates {
-        let handle = Handle::from_path(candidate)?;
-        if stderr_handle == handle {
-            println!("{:?} is stderr!", candidate);
-        } else {
-            println!("{:?} is NOT stderr!", candidate);
-        }
-    }
-    Ok(())
-}