feat: Add 5Why_ prefix to all database tables

- Rename all tables with 5Why_ prefix for namespace isolation
- Update models: User.js, Analysis.js, AuditLog.js
- Update routes: llmConfig.js
- Update scripts: seed-test-users.js, add-deepseek-config.js, add-ollama-config.js
- Add migrate-table-prefix.js script for database migration
- Update db_schema.sql with new table names
- Update views: 5Why_user_analysis_stats, 5Why_recent_analyses

Tables renamed:
- users -> 5Why_users
- analyses -> 5Why_analyses
- analysis_perspectives -> 5Why_analysis_perspectives
- analysis_whys -> 5Why_analysis_whys
- llm_configs -> 5Why_llm_configs
- system_settings -> 5Why_system_settings
- audit_logs -> 5Why_audit_logs
- sessions -> 5Why_sessions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

models/User.js

@@ -12,7 +12,7 @@ class User {
   static async findById(id) {
     try {
       const [rows] = await pool.execute(
-        'SELECT id, employee_id, username, email, role, department, position, is_active, created_at, last_login_at FROM users WHERE id = ?',
+        'SELECT id, employee_id, username, email, role, department, position, is_active, created_at, last_login_at FROM 5Why_users WHERE id = ?',
         [id]
       );
       return rows[0] || null;
@@ -27,7 +27,7 @@ class User {
   static async findByEmail(email) {
     try {
       const [rows] = await pool.execute(
-        'SELECT * FROM users WHERE email = ? AND is_active = 1',
+        'SELECT * FROM 5Why_users WHERE email = ? AND is_active = 1',
         [email]
       );
       return rows[0] || null;
@@ -42,7 +42,7 @@ class User {
   static async findByEmployeeId(employeeId) {
     try {
       const [rows] = await pool.execute(
-        'SELECT * FROM users WHERE employee_id = ? AND is_active = 1',
+        'SELECT * FROM 5Why_users WHERE employee_id = ? AND is_active = 1',
         [employeeId]
       );
       return rows[0] || null;
@@ -69,7 +69,7 @@ class User {
       const passwordHash = await bcrypt.hash(password, 10);
 
       const [result] = await pool.execute(
-        `INSERT INTO users (employee_id, username, email, password_hash, role, department, position)
+        `INSERT INTO 5Why_users (employee_id, username, email, password_hash, role, department, position)
          VALUES (?, ?, ?, ?, ?, ?, ?)`,
         [employee_id, username, email, passwordHash, role, department, position]
       );
@@ -91,7 +91,7 @@ class User {
 
     try {
       await pool.execute(
-        `UPDATE users
+        `UPDATE 5Why_users
          SET username = ?, email = ?, role = ?, department = ?, position = ?, is_active = ?
          WHERE id = ?`,
         [username, email, role, department, position, is_active, id]
@@ -110,7 +110,7 @@ class User {
     try {
       const passwordHash = await bcrypt.hash(newPassword, 10);
       await pool.execute(
-        'UPDATE users SET password_hash = ? WHERE id = ?',
+        'UPDATE 5Why_users SET password_hash = ? WHERE id = ?',
         [passwordHash, id]
       );
       return true;
@@ -125,7 +125,7 @@ class User {
   static async updateLastLogin(id) {
     try {
       await pool.execute(
-        'UPDATE users SET last_login_at = CURRENT_TIMESTAMP WHERE id = ?',
+        'UPDATE 5Why_users SET last_login_at = CURRENT_TIMESTAMP WHERE id = ?',
         [id]
       );
     } catch (error) {
@@ -138,8 +138,8 @@ class User {
    */
   static async getAll(page = 1, limit = 10, filters = {}) {
     const offset = (page - 1) * limit;
-    let query = 'SELECT id, employee_id, username, email, role, department, position, is_active, created_at FROM users';
-    let countQuery = 'SELECT COUNT(*) as total FROM users';
+    let query = 'SELECT id, employee_id, username, email, role, department, position, is_active, created_at FROM 5Why_users';
+    let countQuery = 'SELECT COUNT(*) as total FROM 5Why_users';
     const whereParams = [];
     const whereClauses = [];
 
@@ -167,8 +167,9 @@ class User {
     query += ' ORDER BY created_at DESC LIMIT ? OFFSET ?';
 
     try {
-      const [rows] = await pool.execute(query, [...whereParams, limit, offset]);
-      const [countResult] = await pool.execute(countQuery, whereParams);
+      // 使用 query 而非 execute，因為 LIMIT 和 OFFSET 參數需要數字類型
+      const [rows] = await pool.query(query, [...whereParams, parseInt(limit), parseInt(offset)]);
+      const [countResult] = await pool.query(countQuery, whereParams);
 
       return {
         data: rows,
@@ -190,7 +191,7 @@ class User {
   static async delete(id) {
     try {
       await pool.execute(
-        'UPDATE users SET is_active = 0 WHERE id = ?',
+        'UPDATE 5Why_users SET is_active = 0 WHERE id = ?',
         [id]
       );
       return true;
@@ -204,7 +205,7 @@ class User {
    */
   static async hardDelete(id) {
     try {
-      await pool.execute('DELETE FROM users WHERE id = ?', [id]);
+      await pool.execute('DELETE FROM 5Why_users WHERE id = ?', [id]);
       return true;
     } catch (error) {
       throw new Error(`Error hard deleting user: ${error.message}`);
@@ -217,7 +218,7 @@ class User {
   static async getStats(userId) {
     try {
       const [rows] = await pool.execute(
-        'SELECT * FROM user_analysis_stats WHERE user_id = ?',
+        'SELECT * FROM 5Why_user_analysis_stats WHERE user_id = ?',
         [userId]
       );
       return rows[0] || null;