* refactor(ecstore): add accessor methods for service globals
Phase 3 of global singleton consolidation. Add ECStore accessor
methods that delegate to process-global service singletons,
providing a unified API through ECStore.
New methods:
- notification_system() — delegates to notification_sys global
- bucket_metadata_sys() — delegates to bucket metadata global
- endpoints() — delegates to endpoints global
- region() — delegates to region global
- tier_config_mgr() — delegates to tier config global
- server_config() — delegates to server config global
- storage_class() — delegates to storage class global
1161 tests pass, clippy clean, formatting clean.
* fix: use imported functions instead of fully-qualified paths
Address review comments: use imported functions instead of
crate:: paths to avoid unused import warnings.
1160 tests pass, clippy clean.
* fix(ecstore): remove unused service imports
