feat: add database, role & privilege management

Add Admin sidebar tab with database/role management panels, role manager
workspace tab, and privilege dialogs. Backend provides 10 new Tauri
commands for CRUD on databases, roles, and privileges with read-only
mode enforcement. Context menus on schema tree nodes allow dropping
databases and viewing/granting table privileges.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-tauri/src/commands/data.rs

@@ -2,15 +2,12 @@ use crate::commands::queries::pg_value_to_json;
 use crate::error::{TuskError, TuskResult};
 use crate::models::query_result::PaginatedQueryResult;
 use crate::state::AppState;
+use crate::utils::escape_ident;
 use serde_json::Value;
 use sqlx::{Column, Row, TypeInfo};
 use std::time::Instant;
 use tauri::State;
 
-fn escape_ident(name: &str) -> String {
-    format!("\"{}\"", name.replace('"', "\"\""))
-}
-
 #[tauri::command]
 pub async fn get_table_data(
     state: State<'_, AppState>,