…dynamic MYX import)

Backport two commits made directly in core since the last mobile→core sync:
- Add stopEligibilityMonitoring() method to disable geo-blocking checks
  when useExternalServices is toggled off (core 902236dba)
- Dynamic import for MYXProvider to avoid bundling heavy MYX dependencies
  in extension until MYX fixes their package (core ee7281491)

…ar centralization

- Restructure PerpsControllerConfig: flat MYX fields → nested providerCredentials.{hyperliquid,myx}
- Inject HL builder fee addresses via config instead of hardcoded constants
- Move all process.env reads from Engine init to createMobileClientConfig() in mobileInfrastructure adapter
- Fix MYX dynamic import race condition: await in non-async → .then()/.catch()

- Extract #assignActiveProvider from #createProviders, called after
  await Promise.all([wait, myxRegistrationPromise]) so MYX has
  registered before active provider is assigned
- Extract firstNonEmpty and resolveMyxAuthConfig as exported pure
  functions (testable without --experimental-vm-modules)
- Fix switchProvider test: mock init on reinit call since import()
  rejects in Jest
- 100% new code coverage (15/15 lines)

- Add createMobileClientConfig to test mock factory (CI fix)
- Distinguish module-not-found from runtime errors in MYX .catch()

…g, builder address

- Test MYX dynamic import catch: module-not-found → debug log
- Test stopEligibilityMonitoring defers refreshEligibility
- Test testnet builder address selection in HyperLiquidProvider
- Test createMobileClientConfig default config shape
- Harden catch handler for cross-realm errors (instanceof fails)

…lity

Extract .then()/.catch() callbacks from the MYX dynamic import into
protected methods (registerMYXProvider, handleMYXImportError) so they
can be tested directly. Jest rejects dynamic import() without
--experimental-vm-modules, making inline callbacks untestable.

New code coverage: 97% (33/34 changed lines).

Switch from import() to require() for MYX provider dynamic loading.
Both achieve lazy loading; require() works with Jest module mocking.
Add integration test covering the full init → MYX registration path.

New code coverage: 96% (26/27 changed lines).

Replace broad regex /cannot find|not found|module/ with precise
error.code === 'MODULE_NOT_FOUND' check. Only Node's actual module
resolution failures are treated as expected; constructor/config
errors now correctly route to Sentry via logError.

…iles

Investigation of PerpsController.ts growth (3,343 → 4,689 lines in 6 weeks)
and HyperLiquidProvider.ts (8,342 lines). Documents root causes, phased
extraction plan, and CI guardrails to prevent re-growth.

…shaking

require() defeats webpack code splitting — only import() enables true
tree-shaking so MYX is excluded from the extension bundle. Remove the
integration test that depended on require() resolution (Jest can't
resolve dynamic import() without --experimental-vm-modules); unit tests
for registerMYXProvider and handleMYXImportError remain.