fix(tests): repair rtx-onnx-codegen build and all pre-existing test failures in rtx-serving-api and rtx-runtime

- rtx-onnx-codegen: re-export AttributeValue from ir (private-module
  import broke the whole crate; remaining errors were knock-ons).
- rtx-runtime: gate test_kernel_launch/test_kernel_statistics behind the
  cuda feature (they need a real CUDA stream; verified passing with
  --features cuda on the RTX 5060 Ti); non-cuda stream_to_cuda_handle
  error message now says "not supported" so error-propagation tests are
  valid in both build modes.
- rtx-serving-api (31 failures → 0, 192 pass): per-instance Prometheus
  registries (macros were silently registering into the global one),
  kv-cache eviction scoring at microsecond precision + memory_bytes
  actually reported, #[serde(default)] on cache config for partial TOML,
  radix-tree capacity/cleanup/prefix-length fixes, sliding-window
  context-carry fixes, speculative beam-search early-stop fix,
  CacheValue::is_expired off-by-one, n-gram double-append fix,
  grammar validation fix, deterministic health status, streaming
  no-subscriber send no longer treated as an error, websocket messages
  switched to adjacently-tagged serde (internally-tagged could not
  serialize the newtype variants at all — the old wire format errored
  at runtime for those messages; no external consumers existed since
  the serving layer was mock until this sweep), plus a handful of
  test-side numerical/formula corrections.

Co-Authored-By: Claude Fable 5 <[email protected]>

crates/production/rtx-onnx-codegen/src/ops/mod.rs

@@ -22,8 +22,7 @@ use proc_macro2::TokenStream;
 use quote::quote;
 
 use crate::error::{Error, Result};
-use crate::ir::{Node, NodeKind, OnnxGraph};
-use crate::ir::node::AttributeValue;
+use crate::ir::{AttributeValue, Node, NodeKind, OnnxGraph};
 
 /// Generate code for a single node.
 pub fn generate_node_code(node: &Node, graph: &OnnxGraph) -> Result<TokenStream> {