feat: implement user authentication system

- Add SessionManager for managing user sessions (singleton pattern)
- Add BIPUsersDAO for database authentication
- Add LoginDialog component for username/password login
- Add UserSelectionDialog component for admin user selection
- Support silent login by computer name
- Implement main page with navigation to Extractor and Cleaner

Database:
- Table: dbo_BIPUsers
- Fields: UserName, Password, UserType, ComputerNmae

UI Flow:
1. Silent login on startup via computer name
2. Show login dialog if silent login fails
3. Display main page with user info and navigation
4. Support logout and re-login

src/main/services/user/session-manager.ts

@@ -0,0 +1,185 @@
+/**
+ * User Session Manager - Singleton pattern for managing authenticated user session
+ *
+ * Mimics the Python SessionManager functionality:
+ * - Singleton pattern to maintain user state throughout application lifecycle
+ * - Support for username/password authentication
+ * - Support for silent login by computer name
+ * - Admin user can switch to other users
+ */
+
+import type { UserInfo } from '../../types/user.types'
+
+/**
+ * Session Manager Class
+ */
+export class SessionManager {
+  private static instance: SessionManager | null = null
+  private currentUser: UserInfo | null = null
+  private originalAdminUser: UserInfo | null = null
+  private initialized: boolean = false
+
+  private constructor() {
+    if (this.initialized) {
+      return
+    }
+    this.initialized = true
+  }
+
+  /**
+   * Get the singleton instance
+   */
+  public static getInstance(): SessionManager {
+    if (SessionManager.instance === null) {
+      SessionManager.instance = new SessionManager()
+    }
+    return SessionManager.instance
+  }
+
+  /**
+   * Authenticate and login a user
+   * @param username - The username to authenticate
+   * @param password - The password to verify
+   * @returns True if login successful, false otherwise
+   */
+  public async login(username: string, password: string): Promise<boolean> {
+    try {
+      const { BIPUsersDAO } = await import('./bip-users-dao')
+      const dao = new BIPUsersDAO()
+      const userInfo = await dao.authenticate(username, password)
+
+      if (userInfo) {
+        this.currentUser = {
+          id: userInfo.id,
+          username: userInfo.username,
+          userType: userInfo.userType
+        }
+        return true
+      }
+      return false
+    } catch (error) {
+      console.error('[SessionManager] Login error:', error)
+      return false
+    }
+  }
+
+  /**
+   * Attempt silent login using computer name
+   * @returns True if login successful, false otherwise
+   */
+  public async loginByComputerName(): Promise<boolean> {
+    try {
+      const { BIPUsersDAO } = await import('./bip-users-dao')
+      const dao = new BIPUsersDAO()
+      const computerName = require('os').hostname()
+      const userInfo = await dao.authenticateByComputerName(computerName)
+
+      if (userInfo) {
+        this.currentUser = {
+          id: userInfo.id,
+          username: userInfo.username,
+          userType: userInfo.userType
+        }
+        return true
+      }
+      return false
+    } catch (error) {
+      console.error('[SessionManager] Silent login error:', error)
+      return false
+    }
+  }
+
+  /**
+   * Logout the current user and clear session
+   */
+  public logout(): void {
+    this.currentUser = null
+    this.originalAdminUser = null
+  }
+
+  /**
+   * Check if a user is currently authenticated
+   */
+  public isAuthenticated(): boolean {
+    return this.currentUser !== null
+  }
+
+  /**
+   * Check if the current user is an admin
+   */
+  public isAdmin(): boolean {
+    return this.currentUser?.userType === 'Admin'
+  }
+
+  /**
+   * Check if the current user is a guest
+   */
+  public isGuest(): boolean {
+    return this.currentUser?.userType === 'Guest'
+  }
+
+  /**
+   * Get the current username
+   */
+  public getUsername(): string | null {
+    return this.currentUser?.username ?? null
+  }
+
+  /**
+   * Get the current user type
+   */
+  public getUserType(): string | null {
+    return this.currentUser?.userType ?? null
+  }
+
+  /**
+   * Get all current user information
+   */
+  public getUserInfo(): UserInfo | null {
+    return this.currentUser
+  }
+
+  /**
+   * Switch to a different user (Admin only feature)
+   * @param userInfo - User info to switch to
+   * @returns True if switch successful
+   */
+  public switchUser(userInfo: UserInfo): boolean {
+    if (!this.currentUser) {
+      return false
+    }
+
+    // Store original admin user for reference
+    if (!this.originalAdminUser) {
+      this.originalAdminUser = { ...this.currentUser }
+    }
+
+    this.currentUser = {
+      id: userInfo.id,
+      username: userInfo.username,
+      userType: userInfo.userType
+    }
+    return true
+  }
+
+  /**
+   * Get the original Admin user before any user switch
+   */
+  public getOriginalAdmin(): UserInfo | null {
+    return this.originalAdminUser
+  }
+
+  /**
+   * Get all users from database (for Admin user selection)
+   */
+  public async getAllUsers(): Promise<UserInfo[]> {
+    try {
+      const { BIPUsersDAO } = await import('./bip-users-dao')
+      const dao = new BIPUsersDAO()
+      return await dao.getAllUsers()
+    } catch (error) {
+      console.error('[SessionManager] Get all users error:', error)
+      return []
+    }
+  }
+}