Support for Canadian (CA) Data Residency

### Problem Statement

I’d like to request support for Canadian data residency as an additional region option alongside the current US and EU offerings.

Use Case:

Our organization is based in Canada and must comply with local data privacy laws. While we value Sentry’s hosted platform and features, the lack of a Canadian-hosted option presents a challenge for us in maintaining compliance and meeting client expectations.

### Solution Brainstorm

Introduce Canada (CA) as a selectable region for data storage and processing — ideally leveraging infrastructure within Canadian cloud regions (e.g., AWS Canada Central).

### Product Area

Other

No files, tests, or entry points are named in the issue. Start by locating how the existing US and EU regions are configured and how hosted data storage and processing are provisioned, including whether AWS Canada Central is supported. Done means defining the scope and implementation path for a selectable Canadian region.

Written by the indexing model from the issue text.