feat: add bundled Remote Config defaults

[shameondev]

Summary

• add a synchronous class API usable before SDK initialization, plus an instance forwarder
• read only qonversion_remote_config_defaults.json from the signed app main bundle
• validate the exact configurator schema-1 artifact, framed digest, canonical bytes, limits, portable numbers and Unicode surrogate pairs
• cache one immutable fail-closed document and distinguish a present JSON null from a missing/corrupt key
• pin exact configurator goldens for raw bytes, all JSON shapes and numeric boundaries

Safety boundary

This is an additive bundled-default getter stacked on persistent LKG #753. It does not add the requested Fetched/Active state machine, network endpoint, identity orchestration, or change legacy fallback behavior. Missing/corrupt artifacts return nil and never consult Documents, cache, singleton state, identity, or network.

Verification

• production store clang -fsyntax-only
• project.pbxproj plutil -lint
• three fixture SHA-256 values match configurator producer goldens
• standalone contract harnesses for standard/all-types/numeric/surrogate fixtures
• independent agent review approved after portable number and Unicode boundary fixes

Full XCTest requires GitHub CI because this host has Command Line Tools but no full Xcode installation.

[shameondev]

Консолидировано в release-train PR (один PR на репозиторий). Ветка сохранена.