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/app/state/runtime.rs

@@ -4,20 +4,7 @@
 use serde::{Deserialize, Serialize};
 use std::path::PathBuf;
 
-/// Cumulative token/latency counters for a session, persisted alongside it.
-#[derive(Debug, Clone, Copy, Serialize, Deserialize, Default)]
-pub struct UsageStats {
-    pub tokens_in: u64,
-    pub tokens_out: u64,
-    #[serde(default)]
-    pub last_tokens_in: u64,
-    #[serde(default)]
-    pub last_tokens_out: u64,
-    pub api_calls: u64,
-    pub review_tokens: u64,
-    pub total_ms: u64,
-}
-
+pub use zesdex_entities::seaorm::common::usage::UsageStats;
 /// Mutable, serializable state for one session: chat history, tool
 /// results, pending tools, background jobs, and lesson/review counters
 /// shown in the TUI status bar.
@@ -55,16 +42,7 @@ pub struct SessionRuntime {
     pub hive_mind_converged: bool,
 }
 
-/// Record of one completed tool invocation, kept for transcript/history.
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct ToolCallResult {
-    pub tool_call_id: String,
-    pub tool_name: String,
-    pub output: String,
-    pub is_error: bool,
-    pub duration_ms: u64,
-}
-
+pub use zesdex_entities::seaorm::common::tool_result::ToolCallResult;
 /// A tool call awaiting execution, along with which execution model
 /// (inline, deferred, async) it should run under.
 #[derive(Debug, Clone, Serialize, Deserialize)]