refactor(ramps): ramps controller geolocation rename (#7563)

## Explanation

### Current State and Why It Needs to Change

The RampsController currently uses "geolocation" terminology
(`geolocation` state, `updateGeolocation()` method), which implies a
read-only, automatically-detected value. However, we plan to allow users
to manually change their region in the future, so the naming should
reflect that it's a user-selectable region rather than just a detected
geolocation.

Additionally, consumers must manually call `updateGeolocation()` after
creating the controller, which is error-prone and lacks a clear
initialization pattern.

### Solution and How It Works

This PR refactors the controller to use "userRegion" terminology and
introduces proper initialization:

1. **Renamed state and methods**: `geolocation` → `userRegion`,
`updateGeolocation()` → `updateUserRegion()`
2. **Added `init()` method**: Encapsulates initialization logic,
automatically fetches user region at startup
3. **Added `setUserRegion()` method**: Allows manual region setting
without geolocation API, preparing for future UI feature

### Breaking Changes

- `geolocation` state property → `userRegion`
- `updateGeolocation()` method → `updateUserRegion()`
- Removed deprecated `selectGeolocation` and `selectGeolocationRequest`
selectors
- Removed deprecated `useRampsGeolocation()` hook
- Consumers should use `selectUserRegion`, `selectUserRegionRequest`,
and `useRampsUserRegion()` instead

### Why Multiple Packages Were Updated

This refactor touches both the core controller package and the mobile
app because:
- Core package contains the controller implementation and public API
- Mobile app contains initialization, selectors, hooks, and tests that
consume the controller

All changes are coordinated to ensure consistent API updates and proper
migration from deprecated names.

## References

<!--
Are there any issues that this pull request is tied to?
Are there other links that reviewers should consult to understand these
changes better?
Are there client or consumer pull requests to adopt any breaking
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For example:

* Fixes #12345
* Related to #67890
-->

Mobile PR that adopts the breaking changes:
MetaMask/metamask-mobile#24280

## Checklist

- [ ] I've updated the test suite for new or updated code as appropriate
- [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs)
- [ ] I've introduced [breaking
changes](https://github.com/MetaMask/core/tree/main/docs/breaking-changes.md)
in this PR and have prepared draft pull requests for clients and
consumer packages to resolve them

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **BREAKING**: Rename geolocation API
> 
> - State `geolocation` → `userRegion`; method `updateGeolocation()` →
`updateUserRegion()` with updated request cache keys and tests
> 
> **New APIs**
> 
> - Add `init()` to fetch initial `userRegion` on startup (graceful
failure)
> - Add `setUserRegion(region)` to manually set region and fetch
eligibility
> 
> **Behavioral updates**
> 
> - Normalize region to lowercase; automatically fetch eligibility after
`updateUserRegion`
> - Clear stale `eligibility` on failures only if region still matches;
prevent race-based overwrites
> - `updateEligibility(isoCode)` only updates state when `userRegion`
matches the isoCode/undefined
> - Handle null/undefined geolocation results
> 
> **Misc**
> 
> - Update `createRequestSelector` examples and tests to reference
`updateUserRegion`
> - Changelog updated
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
ab80f89. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: georgeweiler

packages/ramps-controller/CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- **BREAKING:** Rename `geolocation` to `userRegion` and `updateGeolocation()` to `updateUserRegion()` in RampsController ([#7563](https://github.com/MetaMask/core/pull/7563))
+
 - Bump `@metamask/controller-utils` from `^11.17.0` to `^11.18.0` ([#7583](https://github.com/MetaMask/core/pull/7583))
 
 ## [2.1.0]
@@ -21,6 +23,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add request caching infrastructure with TTL, deduplication, and abort support ([#7536](https://github.com/MetaMask/core/pull/7536))
 
+- Add `init()` and `setUserRegion()` methods to RampsController ([#7563](https://github.com/MetaMask/core/pull/7563))
+
 ### Changed
 
 - Bump `@metamask/controller-utils` from `^11.16.0` to `^11.17.0` ([#7534](https://github.com/MetaMask/core/pull/7534))