fix: Fix test failures in OVSM and AI service

Fixed two test failures:

1. **OVSM varargs test** (crates/ovsm/tests/varargs_tests.rs)
   - Issue: Test used `product` as function name, which conflicts with built-in `product` function
   - Fix: Renamed test function to `multiply-all` to avoid name collision
   - Result: test_varargs_with_accumulator now passes

2. **AI service endpoint detection** (src/services/ai_service.rs)
   - Issue: `with_api_url()` didn't check if custom URL is OpenAI-compatible
   - Fix: Added OpenAI-compatibility check for custom URLs (contains "/v1/chat/completions" or "openai.com")
   - Result: test_endpoint_detection now passes correctly

Test Results:
- OVSM: 14/14 varargs tests passing ✅
- OSVM lib: 456/456 tests passing ✅
- Total: 470 tests passing, 0 failures ✅

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: 0xrinegade

crates/ovsm/tests/varargs_tests.rs

@@ -164,14 +164,14 @@ fn test_varargs_rest_without_name() {
 #[test]
 fn test_varargs_with_accumulator() {
     let source = r#"
-(defun product (&rest numbers)
+(defun multiply-all (&rest numbers)
   (do
     (define result 1)
     (for (n numbers)
       (set! result (* result n)))
     result))
 
-(product 2 3 4)
+(multiply-all 2 3 4)
 "#;
     let result = eval_lisp(source).unwrap();
     assert_eq!(result, Value::Int(24));

src/services/ai_service.rs

@@ -173,11 +173,16 @@ impl AiService {
         };
 
         // Override with custom URL if provided (for compatibility)
-        let api_url = custom_api_url.unwrap_or(ai_config.api_url.clone());
+        let api_url = custom_api_url.clone().unwrap_or(ai_config.api_url.clone());
         let api_key = ai_config.api_key.clone();
 
         // Determine if this is OpenAI-compatible
-        let use_openai = ai_config.is_openai_compatible();
+        // If custom URL provided, check it directly; otherwise use config
+        let use_openai = if custom_api_url.is_some() {
+            api_url.contains("/v1/chat/completions") || api_url.contains("openai.com")
+        } else {
+            ai_config.is_openai_compatible()
+        };
 
         // Warn if OpenAI-compatible but no key
         if use_openai && api_key.is_none() && debug_mode {