chore(lint): remove unused imports, variables, and redundant mut bindings

Eliminate low-risk clippy warnings as part of the strict lint backlog (#409):

- Remove unused `uuid::Uuid` imports from slack and telegram channels
- Remove unnecessary `mut` and redundant rebindings in agent loop
- Prefix unused `channel_id` variable in discord channel
- Remove unused test imports (`ChatResponse`, `ToolCall`, `TempDir`, `Path`)

src/agent/loop_.rs

@@ -489,10 +489,8 @@ pub(crate) async fn run_tool_call_loop(
         };
 
         let response_text = response;
-        let mut assistant_history_content = response_text.clone();
+        let assistant_history_content = response_text.clone();
         let (parsed_text, tool_calls) = parse_tool_calls(&response_text);
-        let mut parsed_text = parsed_text;
-        let mut tool_calls = tool_calls;
 
         if tool_calls.is_empty() {
             // No tool calls — this is the final response

src/channels/discord.rs

@@ -344,7 +344,7 @@ impl Channel for DiscordChannel {
                     }
 
                     let message_id = d.get("id").and_then(|i| i.as_str()).unwrap_or("");
-                    let channel_id = d.get("channel_id").and_then(|c| c.as_str()).unwrap_or("").to_string();
+                    let _channel_id = d.get("channel_id").and_then(|c| c.as_str()).unwrap_or("").to_string();
 
                     let channel_msg = ChannelMessage {
                         id: if message_id.is_empty() {

src/channels/mod.rs

@@ -1065,7 +1065,7 @@ mod tests {
     use super::*;
     use crate::memory::{Memory, MemoryCategory, SqliteMemory};
     use crate::observability::NoopObserver;
-    use crate::providers::{ChatMessage, ChatResponse, Provider, ToolCall};
+    use crate::providers::{ChatMessage, Provider};
     use crate::tools::{Tool, ToolResult};
     use std::collections::HashMap;
     use std::sync::atomic::{AtomicUsize, Ordering};

src/channels/slack.rs

@@ -1,6 +1,5 @@
 use super::traits::{Channel, ChannelMessage};
 use async_trait::async_trait;
-use uuid::Uuid;
 
 /// Slack channel — polls conversations.history via Web API
 pub struct SlackChannel {

src/channels/telegram.rs

@@ -3,7 +3,6 @@ use async_trait::async_trait;
 use reqwest::multipart::{Form, Part};
 use std::path::Path;
 use std::time::Duration;
-use uuid::Uuid;
 
 /// Telegram's maximum message length for text messages
 const TELEGRAM_MAX_MESSAGE_LENGTH: usize = 4096;

src/config/schema.rs

@@ -1810,7 +1810,6 @@ fn sync_directory(_path: &Path) -> Result<()> {
 mod tests {
     use super::*;
     use std::path::PathBuf;
-    use tempfile::TempDir;
 
     // ── Defaults ─────────────────────────────────────────────
 

src/tools/git_operations.rs

@@ -2,8 +2,6 @@ use super::traits::{Tool, ToolResult};
 use crate::security::{AutonomyLevel, SecurityPolicy};
 use async_trait::async_trait;
 use serde_json::json;
-#[cfg(test)]
-use std::path::Path;
 use std::sync::Arc;
 
 /// Git operations tool for structured repository management.