fix(server): fix doc_lazy_continuation clippy warnings

Fix doc comment formatting in multi_agent_handlers.rs:
- Add blank line after first line of doc comments for resolve_llm_config
- Add blank line after first line of doc comments for get_role_extra_str
- Move helper functions after resolve_llm_config to maintain logical order

Fixes clippy doc_lazy_continuation warnings.

Part of: #443

Author: AlexMikhalev

terraphim_server/src/workflows/multi_agent_handlers.rs

@@ -77,51 +77,37 @@ impl MultiAgentWorkflowExecutor {
                 // Check if there's a global LLM config section
                 let default_role_name = "Default".into();
                 if let Some(default_role) = config.roles.get(&default_role_name) {
-                    if let Some(provider) = default_role.extra.get("llm_provider") {
-                        if let Some(provider_str) = provider.as_str() {
-                            resolved.llm_provider = Some(provider_str.to_string());
-                        }
+                    if let Some(s) = Self::get_role_extra_str(&default_role.extra, "llm_provider") {
+                        resolved.llm_provider = Some(s.to_string());
                     }
-                    if let Some(model) = default_role.extra.get("llm_model") {
-                        if let Some(model_str) = model.as_str() {
-                            resolved.llm_model = Some(model_str.to_string());
-                        }
+                    if let Some(s) = Self::get_role_extra_str(&default_role.extra, "llm_model") {
+                        resolved.llm_model = Some(s.to_string());
                     }
-                    if let Some(base_url) = default_role.extra.get("llm_base_url") {
-                        if let Some(base_url_str) = base_url.as_str() {
-                            resolved.llm_base_url = Some(base_url_str.to_string());
-                        }
+                    if let Some(s) = Self::get_role_extra_str(&default_role.extra, "llm_base_url") {
+                        resolved.llm_base_url = Some(s.to_string());
                     }
                 }
 
                 // Check role-specific config
                 let role_name_key = role_name.into();
                 if let Some(role) = config.roles.get(&role_name_key) {
-                    if let Some(provider) = role.extra.get("llm_provider") {
-                        if let Some(provider_str) = provider.as_str() {
-                            resolved.llm_provider = Some(provider_str.to_string());
-                        }
+                    if let Some(s) = Self::get_role_extra_str(&role.extra, "llm_provider") {
+                        resolved.llm_provider = Some(s.to_string());
                     }
-                    if let Some(model) = role.extra.get("llm_model") {
-                        if let Some(model_str) = model.as_str() {
-                            resolved.llm_model = Some(model_str.to_string());
-                        }
+                    if let Some(s) = Self::get_role_extra_str(&role.extra, "llm_model") {
+                        resolved.llm_model = Some(s.to_string());
                     }
-                    if let Some(base_url) = role.extra.get("llm_base_url") {
-                        if let Some(base_url_str) = base_url.as_str() {
-                            resolved.llm_base_url = Some(base_url_str.to_string());
-                        }
+                    if let Some(s) = Self::get_role_extra_str(&role.extra, "llm_base_url") {
+                        resolved.llm_base_url = Some(s.to_string());
                     }
-                    if let Some(temp) = role.extra.get("llm_temperature") {
-                        if let Some(temp_val) = temp.as_f64() {
-                            resolved.llm_temperature = Some(temp_val);
-                        }
+                    if let Some(v) = Self::get_role_extra_f64(&role.extra, "llm_temperature") {
+                        resolved.llm_temperature = Some(v);
                     }
                 }
             }
         }
 
-        // Override with request-level config (highest priority)
+        // Override with request-level config if provided
         if let Some(req_config) = request_config {
             if let Some(provider) = &req_config.llm_provider {
                 resolved.llm_provider = Some(provider.clone());
@@ -149,6 +135,32 @@ impl MultiAgentWorkflowExecutor {
         resolved
     }
 
+    /// Get a string value from Role.extra, checking both flat and nested paths.
+    ///
+    /// Due to `#[serde(flatten)]` on `Role.extra`, config JSON with `"extra": {"key": "val"}`
+    /// results in `extra["extra"]["key"]` rather than `extra["key"]`.
+    fn get_role_extra_str<'a>(
+        extra: &'a AHashMap<String, serde_json::Value>,
+        key: &str,
+    ) -> Option<&'a str> {
+        extra.get(key).and_then(|v| v.as_str()).or_else(|| {
+            extra
+                .get("extra")
+                .and_then(|v| v.get(key))
+                .and_then(|v| v.as_str())
+        })
+    }
+
+    /// Get an f64 value from Role.extra, checking both flat and nested paths.
+    fn get_role_extra_f64(extra: &AHashMap<String, serde_json::Value>, key: &str) -> Option<f64> {
+        extra.get(key).and_then(|v| v.as_f64()).or_else(|| {
+            extra
+                .get("extra")
+                .and_then(|v| v.get(key))
+                .and_then(|v| v.as_f64())
+        })
+    }
+
     /// Execute prompt chaining workflow with actual TerraphimAgent
     #[allow(clippy::too_many_arguments)]
     pub async fn execute_prompt_chain(