IT Assets: add Maintenance page with modal form

New database table: maintenance_records
- Fields: asset, start_date, end_date, status (open/in_progress/closed),
  initial_diagnosis, action_taken, action_result

New routes (/maintenance/):
- List with status + asset filters and pagination
- POST /new — create record (editor+); auto-sets asset status to 'maintenance'
- GET /<id>/edit — opens list page with modal pre-filled
- POST /<id>/update — save edits; auto-clears 'maintenance' status on close
- POST /<id>/delete — remove record

UI:
- Bootstrap modal form shared for add and edit
- Clicking any table row opens the modal pre-filled with that row's data
- Asset field locked in edit mode (cannot change asset)
- Delete button per row (with confirmation)
- Sidebar: 'Maintenance' link added under Hardware section

IT_asset_management/app/models/__init__.py

@@ -5,5 +5,6 @@ from app.models.assignment import Assignment
 from app.models.paperwork import Paperwork
 from app.models.audit_log import AuditLog
 from app.models.compliance_check import ComplianceCheck
+from app.models.maintenance import MaintenanceRecord
 
-__all__ = ['AdminUser', 'User', 'Asset', 'Assignment', 'Paperwork', 'AuditLog', 'ComplianceCheck']
+__all__ = ['AdminUser', 'User', 'Asset', 'Assignment', 'Paperwork', 'AuditLog', 'ComplianceCheck', 'MaintenanceRecord']

IT_asset_management/app/models/maintenance.py

@@ -0,0 +1,41 @@
+from datetime import datetime
+from app.extensions import db
+
+MAINTENANCE_STATUSES = [
+    ('open',        'Open / Diagnosed'),
+    ('in_progress', 'In Progress'),
+    ('closed',      'Closed'),
+]
+
+
+class MaintenanceRecord(db.Model):
+    """A maintenance or service event performed on a single asset."""
+    __tablename__ = 'maintenance_records'
+
+    id = db.Column(db.Integer, primary_key=True)
+
+    asset_id = db.Column(db.Integer, db.ForeignKey('assets.id'), nullable=False)
+
+    start_date  = db.Column(db.Date, nullable=False)
+    end_date    = db.Column(db.Date, nullable=True)
+
+    status = db.Column(db.String(20), nullable=False, default='open')
+
+    initial_diagnosis = db.Column(db.Text, nullable=True)
+    action_taken      = db.Column(db.Text, nullable=True)
+    action_result     = db.Column(db.Text, nullable=True)
+
+    created_by_id = db.Column(db.Integer, db.ForeignKey('admin_users.id'), nullable=True)
+    created_at    = db.Column(db.DateTime, default=datetime.utcnow)
+    updated_at    = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    # Relationships
+    asset      = db.relationship('Asset',      backref=db.backref('maintenance_records', lazy='dynamic'))
+    created_by = db.relationship('AdminUser',  foreign_keys=[created_by_id])
+
+    @property
+    def is_open(self):
+        return self.status != 'closed'
+
+    def __repr__(self):
+        return f'<MaintenanceRecord asset={self.asset_id} status={self.status}>'