Add mutation injection test example

Author: Sixzero

examples/test_mutate.jl

@@ -0,0 +1,30 @@
+using OpenRouter
+using OpenRouterCLIProxyAPI
+
+println("=" ^ 60)
+println("TEST 1: BEFORE MUTATE INJECT")
+println("anthropic:anthropic/claude-sonnet-4.5 -> direct Anthropic API")
+println("=" ^ 60)
+
+response1 = aigen("Say 'Hello from before mutate' in exactly those words.",
+    "anthropic:anthropic/claude-sonnet-4.5";
+    streamcallback=HttpStreamCallback(; out=stdout, verbose=true))
+
+println("\n\nResponse: ", response1.content)
+
+println("\n" * "=" ^ 60)
+println("APPLYING MUTATE INJECT...")
+println("=" ^ 60)
+
+setup_cli_proxy!(; mutate=true)
+
+println("\n" * "=" ^ 60)
+println("TEST 2: AFTER MUTATE INJECT (anthropic: prefix)")
+println("anthropic:anthropic/claude-sonnet-4.5 -> now routes to cli_proxy_api")
+println("=" ^ 60)
+
+response2 = aigen("Say 'Hello from after mutate' in exactly those words.",
+    "anthropic:anthropic/claude-sonnet-4.5";
+    streamcallback=HttpStreamCallback(; out=stdout, verbose=true))
+
+println("\n\nResponse: ", response2.content)