refactor: clean codebase - remove dead code, fix warnings, delete unused docs

- Created missing cortex_prompt.txt for engine compilation
- Applied cargo fmt to standardize code formatting
- Auto-fixed clippy warnings with --fix (reduced from 164 to ~128)
- Removed unused code and fixed unused variable warnings
- Deleted outdated documentation files:
  - cortex-cli/COMPREHENSIVE_ANALYSIS.md
  - cortex-cli/DEEP_CODE_REVIEW.md
  - cortex-gui/orchestration/*.md (14 files)
  - cortex-gui/UI_REBASE/*.md (20 files)
  - cortex-gui/PERFORMANCE_FEATURE_ROADMAP.md
  - cortex-gui/FEATURE_IMPROVEMENT_PLAN.md
  - cortex-gui/ZED_VSCODE_COMPARISON_ROADMAP.md
- Fixed dead code warnings with #[allow(dead_code)] where appropriate
- Removed unused imports and collapsed nested conditionals

Author: Cortex Agent

cortex-app-server/src/admin.rs

@@ -483,18 +483,18 @@ async fn list_all_sessions(
         sessions.retain(|s| &s.model == model);
     }
 
-    if let Some(from) = &query.from {
-        if let Ok(from_dt) = chrono::DateTime::parse_from_rfc3339(from) {
-            let from_ts = from_dt.timestamp();
-            sessions.retain(|s| s.created_at >= from_ts);
-        }
+    if let Some(from) = &query.from
+        && let Ok(from_dt) = chrono::DateTime::parse_from_rfc3339(from)
+    {
+        let from_ts = from_dt.timestamp();
+        sessions.retain(|s| s.created_at >= from_ts);
     }
 
-    if let Some(to) = &query.to {
-        if let Ok(to_dt) = chrono::DateTime::parse_from_rfc3339(to) {
-            let to_ts = to_dt.timestamp();
-            sessions.retain(|s| s.created_at <= to_ts);
-        }
+    if let Some(to) = &query.to
+        && let Ok(to_dt) = chrono::DateTime::parse_from_rfc3339(to)
+    {
+        let to_ts = to_dt.timestamp();
+        sessions.retain(|s| s.created_at <= to_ts);
     }
 
     // Sort
@@ -506,7 +506,7 @@ async fn list_all_sessions(
     }
 
     let total = sessions.len();
-    let total_pages = (total + query.limit - 1) / query.limit;
+    let total_pages = total.div_ceil(query.limit);
 
     // Paginate
     let start = (query.page - 1) * query.limit;
@@ -642,14 +642,14 @@ async fn export_sessions_csv(
 
 /// List all shares.
 async fn list_all_shares(
-    State(state): State<Arc<AppState>>,
+    State(_state): State<Arc<AppState>>,
     Query(query): Query<ListSharesQuery>,
 ) -> AppResult<Json<ShareListResponse>> {
     // Get all shares from the manager (assuming it's a user, we get their shares)
     // For admin, we'd need a method to get all shares regardless of user
     // For now, return what's available
 
-    let now = chrono::Utc::now().timestamp();
+    let _now = chrono::Utc::now().timestamp();
 
     // Note: In a real implementation, ShareManager would have a list_all method
     // For now, we use what's available