fix(migration): resolve v1.0.0 password column migration causing login failures (#1059)

Fixes users unable to login after upgrading from v1.0.0 to v1.1.0-dev.16.

The migration was using COALESCE(password_digest, password) which fails in
SQLite when password_digest column doesn't exist in v1.0.0 databases. The
v1.0.0 schema had a 'password' column, not 'password_digest'.

Changes:
- Dynamically detect which password column exists (password vs password_digest)
- Use the correct column in the migration SELECT statement
- Add enhanced trust proxy diagnostics to help debug configuration issues

Tested:
- Created v1.0.0 database with 'password' column
- Verified user login works pre-migration
- Ran migration with fix
- Confirmed password hash preserved and login still works post-migration

backend/app.js

@@ -26,6 +26,8 @@ if (config.trustProxy !== false) {
     console.log(`[Trust Proxy] Disabled (value: false)`);
 }
 
+console.log(`[Trust Proxy] Express setting confirmed:`, app.get('trust proxy'));
+
 // Session store
 const sessionStore = new SequelizeStore({
     db: sequelize,