fix: resolve compiler warnings across crates

- Remove unused assignment to final_output_called (returns immediately after)
- Mark cache_config field as #[allow(dead_code)] (reserved for future use)
- Mark print_status_line method as #[allow(dead_code)] (reserved for future use)

crates/g3-providers/src/anthropic.rs

@@ -125,6 +125,7 @@ pub struct AnthropicProvider {
     model: String,
     max_tokens: u32,
     temperature: f32,
+    #[allow(dead_code)]
     cache_config: Option<String>,
     enable_1m_context: bool,
     thinking_budget_tokens: Option<u32>,