Feature: ticket API layer (single backend behind an interface)

[CoreyAllenAudio]

Context

The app needs to talk to a helpdesk ticket backend (GET/POST). We have one known
backend (the Swagger/REST ticket API). We want clean networking now, with a seam
that allows other backends later — WITHOUT building those other backends yet (YAGNI).

Scope

Define a TicketApi interface and implement ONE concrete adapter for the known
REST endpoints. Additional backends are explicitly out of scope; they'd implement
the same interface in a future issue.

Tasks

• Define a TicketApi interface (e.g. getTickets(), createTicket())
• Add a networking client (HTTP lib of choice)
• Implement one concrete adapter for the known Swagger endpoints
• Map JSON responses to Kotlin data models
• Basic error/timeout handling
• (Optional) a fake/in-memory implementation for previews & tests

Acceptance Criteria

• TicketApi interface exists with GET + POST operations
• One real implementation performs a GET and a POST against the endpoints
• Responses deserialize into typed models
• Adding a second backend requires only a new implementation of the interface

Notes / design

The interface is the extensibility point. Do NOT implement adapters for other
helpdesk products until there's a real need.