feat: add bundled Remote Config defaults

[shameondev]

Summary

• add a synchronous @JvmStatic pre-initialization getter taking only Context and logical key
• read only qonversion_remote_config_defaults.json from app assets
• validate the exact configurator schema-1 artifact, framed digest, canonical bytes, limits, portable numbers and Unicode surrogate pairs
• expose immutable JSON-compatible values in a nullable wrapper so present JSON null differs from missing/corrupt
• cache one fail-closed process document and pin exact configurator goldens

Safety boundary

This is an additive bundled-default getter stacked on persistent LKG #857. It does not add Fetched/Active orchestration, a new network endpoint, identity transitions, or change legacy fallback behavior. It never reads SharedPreferences, singleton state, identity, Documents, or network.

Verification

• 14 focused reader/public API tests pass
• detektAll passes
• :sdk:assembleDebug passes
• independent agent review approved after portable header-number and Unicode surrogate fixes

lintDebug still reports the pre-existing untouched min-API issue in internal/storage/Cache.kt:33; this PR introduces no new lint finding.

[shameondev]

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