Refactor IPC and DTO structures; remove unused code and streamline message handling

- Removed unused structs and methods from `response.rs`, `usage.rs`, and `client.rs`.
- Simplified `Connection` handling in `conn.rs` to only support Unix sockets.
- Updated `IpcServer` to exclusively use Unix sockets and removed TCP handling.
- Cleaned up `editlog.rs` by removing loading and recent entry methods.
- Refactored `memory.rs` to eliminate unused functions related to lesson promotion and retrospective creation.
- Enhanced `search.rs` to support multiple search providers and improved error handling.
- Updated chat view logic to simplify message display and improve user experience.
- Removed deprecated modules and constants from various files to streamline the codebase.

src/app/subagent/spawn.rs

@@ -22,34 +22,8 @@ impl AgentDefinition {
         }
     }
 
-    pub fn with_system_prompt(mut self, prompt: String) -> Self {
-        self.system_prompt = Some(prompt);
-        self
-    }
-
-    pub fn with_allowed_tools(mut self, tools: Vec<String>) -> Self {
-        self.allowed_tools = Some(tools);
-        self
-    }
-
     pub fn with_max_steps(mut self, steps: usize) -> Self {
         self.max_steps = Some(steps);
         self
     }
-
-    pub fn with_temperature(mut self, temp: f32) -> Self {
-        self.temperature = Some(temp);
-        self
-    }
-}
-
-pub fn merge_agent_defs(base: AgentDefinition, overrides: AgentDefinition) -> AgentDefinition {
-    AgentDefinition {
-        name: base.name,
-        role: base.role,
-        system_prompt: overrides.system_prompt.or(base.system_prompt),
-        allowed_tools: overrides.allowed_tools.or(base.allowed_tools),
-        max_steps: overrides.max_steps.or(base.max_steps),
-        temperature: overrides.temperature.or(base.temperature),
-    }
 }