Accounts App
============

**Purpose**: User management, role assignment, team organization, and geographic zone management.

**This app is the foundation** — every other app depends on ``accounts`` for user identity and role-based access control.

Responsibilities
----------------

- User registration and profile management
- Role assignment (seven system roles)
- Team creation and membership management
- Geographic zone definition and assignment
- JWT-based authentication (access + refresh tokens)
- Custom permission classes used by all other apps

Dependencies
------------

None. This is a leaf dependency — other apps import from ``accounts``, but ``accounts`` imports from no other ChargeSol app.

Key Models
----------

- **User** — Extends Django's ``AbstractUser`` with phone, role, zone, and availability flag.
- **Role** — System roles: ``oem``, ``customer``, ``central_ops``, ``field_team``, ``procurement``, ``finance``, ``oem_reporting``.
- **Team** — Groups of field team users, scoped to a zone. Specialization: survey, installation, or both.
- **TeamMembership** — Links users to teams with a role (lead or member).
- **Zone** — Geographic regions (city/district level) that determine team assignment and material stock location.

Business Rules
--------------

- A user belongs to exactly one role.
- A field team user can be a member of multiple teams (e.g., survey team and installation team).
- Teams are scoped to a single zone; users can only be assigned work within their team's zone.
- The ``is_available`` flag on User is checked by the emergency app when searching for backup teams.
- Central Ops users can manage users and teams across all zones.