Refactor and clean up code across multiple modules

- Simplified token type assignment in OAuth service.
- Removed unused session_lock module and re-exported Session from zesdex_entities.
- Cleaned up session entity by removing unnecessary comments and code.
- Consolidated session handling in HTTP handlers for better readability.
- Improved formatting and readability in OAuth repository tests.
- Enhanced session lock repository with clearer match statements.
- Streamlined session repository error handling.
- Refined RNG tests for better clarity.
- Adjusted module visibility and organization in lib.rs.
- Updated IPC client and connection code for better error handling and clarity.
- Improved frame handling in IPC for better readability.
- Organized module imports and added test utilities for IPC.
- Enhanced database connection error handling.
- Simplified JWT token creation error handling.
- Improved password verification error handling.
- Cleaned up state management code for better readability.
- Refactored middleware for session authentication and rate limiting.
- Simplified clipboard utility for better error handling.
- Enhanced logging initialization for better error reporting.
- Improved pagination utility with clearer method annotations.
- Cleaned up sanitization functions for filenames and paths.
- Enhanced slug generation functions for better clarity and usability.

crates/zesdex-backend/src/tool/utility/cd.rs

@@ -1,7 +1,7 @@
 //! `cd` tool: verify and resolve a workspace-relative directory path.
 use super::super::Tool;
 use super::super::ToolCtx;
-use anyhow::{anyhow, Result};
+use anyhow::Result;
 use serde_json::{json, Value};
 
 /// Tool that resolves a workspace-relative path and reports whether it exists and is a dir.
@@ -40,12 +40,9 @@ impl Tool for Cd {
     /// Return: canonical path on success; explicit "does not exist" / "not a directory"
     /// message (still `Ok`) so the model can react without treating it as an error.
     fn run(&self, ctx: &ToolCtx, args: &Value) -> Result<String> {
-        let rel = args
-            .get("path")
-            .and_then(|v| v.as_str())
-            .ok_or_else(|| anyhow!("missing required argument: path"))?;
+        let rel = crate::tool::arg_str(args, "path")?;
 
-        let path = super::super::resolve_path(&ctx.workspaces, rel)?;
+        let path = super::super::resolve_path(&ctx.workspaces, &rel)?;
 
         if !path.exists() {
             return Ok(format!(