feat(postgres): migrate all route files from SQLite to pg pool

- All 16 route files now import pool from ../db directly
- Removed db parameter from all factory functions
- All callbacks replaced with async/await pool.query()
- All ? placeholders converted to $1, $2... numbered params
- datetime('now') → NOW(), INSERT OR IGNORE → ON CONFLICT DO NOTHING
- LIKE → ILIKE for case-insensitive searches
- Error detection: err.code === '23505' for unique violations
- server.js no longer passes pool/db/requireAuth to route factories
- Only ivantiFindings.js still receives pool (pending task 8 rewrite)

backend/middleware/auth.js

@@ -1,7 +1,8 @@
 // Authentication Middleware
+const pool = require('../db');
 
-// Require authenticated user
-function requireAuth(db) {
+// Require authenticated user — no parameters needed, pool is imported directly
+function requireAuth() {
     return async (req, res, next) => {
         const sessionId = req.cookies?.session_id;
 
@@ -10,19 +11,15 @@ function requireAuth(db) {
         }
 
         try {
-            const session = await new Promise((resolve, reject) => {
-                db.get(
-                    `SELECT s.*, u.id as user_id, u.username, u.email, u.role, u.user_group, u.bu_teams, u.is_active
-                     FROM sessions s
-                     JOIN users u ON s.user_id = u.id
-                     WHERE s.session_id = ? AND s.expires_at > datetime('now')`,
-                    [sessionId],
-                    (err, row) => {
-                        if (err) reject(err);
-                        else resolve(row);
-                    }
-                );
-            });
+            const { rows } = await pool.query(
+                `SELECT s.*, u.id as user_id, u.username, u.email, u.role, u.user_group, u.bu_teams, u.is_active
+                 FROM sessions s
+                 JOIN users u ON s.user_id = u.id
+                 WHERE s.session_id = $1 AND s.expires_at > NOW()`,
+                [sessionId]
+            );
+
+            const session = rows[0];
 
             if (!session) {
                 return res.status(401).json({ error: 'Session expired or invalid' });