feat(inference): concrete EAGLE draft model + real tokenizer at the serving boundary

EAGLE (rtx-inference/src/eagle.rs, ~610 lines, mirrors medusa.rs
conventions): EagleDraftHead autoregressive FFN with Concat/Add/
Attention feature fusion, EagleHeads draft model with draft/
draft_steps (per-step top-k for candidate trees) and teacher-forced
training_loss; implements the speculative::EagleDraftModel trait so it
plugs into the orchestration layer. 38 unit tests.

Tokenizer (rtx-inference/src/tokenizer.rs): ServingTokenizer enum —
Vocab (HuggingFace tokenizers, loadable from tokenizer.json) or
ByteLevel fallback preserving previous behavior. rtx-serving-api's
AppState and rtx-streaming's token generator now encode/decode through
it (with_engine_and_tokenizer / set_tokenizer added; existing
signatures unchanged). Also fixes two pre-existing compile errors in
rtx-streaming (missing import, stray .await) that blocked its lib
tests entirely.

Tests: rtx-inference 328 pass, rtx-serving-api 193 pass, rtx-streaming
53 pass (2 pre-existing mock-server connection failures unrelated to
these changes).

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

crates/production/rtx-streaming/src/realtime_pipeline/mod.rs

@@ -251,7 +251,7 @@ mod tests {
         };
 
         let start = Instant::now();
-        let result = pipeline.process_event(event).await;
+        let result = pipeline.process_event(event);
         let latency = start.elapsed();
 
         assert!(result.is_ok());
@@ -293,7 +293,7 @@ mod tests {
                     sequence_number: i as u64,
                 };
 
-                pipeline.process_event(event).await
+                pipeline.process_event(event)
             });
             handles.push(handle);
         }