refactor: replace module-level mutable globals with typed state objects in cloud providers (#2255)

Each cloud module (aws, daytona, digitalocean, gcp, hetzner, sprite) previously
stored per-operation state in bare module-level `let` variables, making them
process-global singletons. This is safe for single-cloud CLI invocations today
but creates latent bugs for multi-cloud orchestration and test isolation.

Replace scattered `let` globals with a single typed `_state` object per module:
- `AwsState` / `resetAwsState()` — 8 fields including `selectedBundle`
- `DaytonaState` / `resetDaytonaState()` — 5 fields
- `DigitalOceanState` / `resetDigitalOceanState()` — 3 fields
- `GcpState` / `resetGcpState()` — 5 fields
- `HetznerState` / `resetHetznerState()` — 3 fields
- `SpriteState` / `resetSpriteState()` — 2 fields

Each module exports a `resetXxxState()` function for test isolation. No function
signatures or existing exports were changed.

Fixes #2251

Agent: issue-fixer

Co-authored-by: B <6723574+louisgv@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 3 people