Refactor apply_cached_repeat_penalty for optimized caching and reuse, add extensive unit tests, and integrate special handling for gemma-specific models.

Removed `test_request.sh`, deprecated functionality, and unused imports; introduced a new CLI tool (`cli.ts`) for testing inference engine and adjusted handling of non-streaming/streaming chat completions.

- Add CPU fallback support for text generation when primary device is unsupported
- Introduce `execute_with_fallback` method to handle device compatibility and shape mismatch errors
- Extend unit tests to reproduce tensor shape mismatch errors specific to model configurations
- Increase HTTP timeout limits in `curl_chat_stream.sh` script for reliable API testing

chat completion endpoint functions with gemma3 (no streaming)

Add benchmarking guide with HTML reporting, Leptos chat crate, and middleware for metrics tracking

crates/legacy-inference-engine/tests/token_output_stream_tests.rs

@@ -0,0 +1,129 @@
+use legacy_inference_engine::token_output_stream::TokenOutputStream;
+use tokenizers::Tokenizer;
+use std::path::PathBuf;
+use anyhow::Result;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // Helper function to create a simple tokenizer for testing
+    fn create_test_tokenizer() -> Result<Tokenizer> {
+        // Create a simple tokenizer from the pretrained model
+        // This uses the tokenizer from the Hugging Face hub
+        let tokenizer = Tokenizer::from_pretrained("google/gemma-2b", None).unwrap();
+        Ok(tokenizer)
+    }
+
+    #[test]
+    fn test_new_token_output_stream() -> Result<()> {
+        let tokenizer = create_test_tokenizer()?;
+        let token_stream = TokenOutputStream::new(tokenizer);
+        
+        // Check that the token stream was created successfully
+        assert!(token_stream.tokenizer().get_vocab(true).len() > 0);
+        Ok(())
+    }
+
+    #[test]
+    fn test_clear() -> Result<()> {
+        let tokenizer = create_test_tokenizer()?;
+        let mut token_stream = TokenOutputStream::new(tokenizer);
+        
+        // Add a token
+        let token_id = token_stream.get_token("<eos>").unwrap();
+        token_stream.next_token(token_id)?;
+        
+        // Clear the stream
+        token_stream.clear();
+        
+        // Check that the stream is empty by trying to decode all
+        let decoded = token_stream.decode_all()?;
+        assert_eq!(decoded, "");
+        
+        Ok(())
+    }
+
+    #[test]
+    fn test_get_token() -> Result<()> {
+        let tokenizer = create_test_tokenizer()?;
+        let token_stream = TokenOutputStream::new(tokenizer);
+        
+        // Get a token that should exist
+        let eos_token = token_stream.get_token("<eos>");
+        assert!(eos_token.is_some());
+        
+        // Get a token that shouldn't exist
+        let nonexistent_token = token_stream.get_token("<this_token_does_not_exist>");
+        assert!(nonexistent_token.is_none());
+        
+        Ok(())
+    }
+
+    #[test]
+    fn test_next_token_and_decode() -> Result<()> {
+        let tokenizer = create_test_tokenizer()?;
+        let mut token_stream = TokenOutputStream::new(tokenizer);
+        
+        // Get some tokens
+        let hello_tokens = token_stream.tokenizer().encode("Hello world", true).unwrap();
+        let token_ids = hello_tokens.get_ids();
+        
+        // Add tokens one by one
+        let mut output = String::new();
+        for &token_id in token_ids {
+            if let Some(text) = token_stream.next_token(token_id)? {
+                output.push_str(&text);
+            }
+        }
+        
+        // Get any remaining text
+        if let Some(rest) = token_stream.decode_rest()? {
+            output.push_str(&rest);
+        }
+        
+        // Check the output
+        assert!(!output.is_empty());
+        assert_eq!(output.trim(), "Hello world");
+        
+        Ok(())
+    }
+
+    #[test]
+    fn test_decode_all() -> Result<()> {
+        let tokenizer = create_test_tokenizer()?;
+        let mut token_stream = TokenOutputStream::new(tokenizer);
+        
+        // Get some tokens
+        let hello_tokens = token_stream.tokenizer().encode("Hello world", true).unwrap();
+        let token_ids = hello_tokens.get_ids();
+        
+        // Add tokens one by one
+        for &token_id in token_ids {
+            token_stream.next_token(token_id)?;
+        }
+        
+        // Decode all
+        let decoded = token_stream.decode_all()?;
+        
+        // Check the output
+        assert_eq!(decoded.trim(), "Hello world");
+        
+        Ok(())
+    }
+
+    #[test]
+    fn test_into_inner() -> Result<()> {
+        let tokenizer = create_test_tokenizer()?;
+        let token_stream = TokenOutputStream::new(tokenizer);
+        
+        // Get the inner tokenizer
+        let inner_tokenizer = token_stream.into_inner();
+        
+        // Check that the inner tokenizer works
+        let encoded = inner_tokenizer.encode("Test", true).unwrap();
+        assert!(encoded.get_ids().len() > 0);
+        
+        Ok(())
+    }
+}