feat: persist Remote Config last-known-good

[shameondev]

Outcome

Adds persistent Last Known Good (LKG) delivery for Remote Configs so a process restart plus transient API/network failure returns the last valid response before falling back to the bundled file. Also exposes the durable frozen assignment provenance.

Stacked on #856 so the release contains both persistent fallback and restored TLS certificate/hostname verification.

Reliability contract

• scope cache entries by project key, environment, Qonversion user, and context key
• capture identity/generation before requests; identify/logout/restore cannot save or deliver another user's response
• reissue concurrent single/list waiters exactly once across identity transitions
• use network success first, then persistent LKG, then bundled fallback; merge missing list contexts without replacing valid LKG with static defaults
• fall back on transport failures, response parsing, HTTP 408/429, and 5xx; never mask cancellation, authentication, unknown SDK errors, or other 4xx
• validate that single/list responses contain only the requested, unique context keys; preserve authoritative no-config semantics and remove stale LKG
• cap the managed/indexed cache during normal writes at 8 scopes, 64 configs per scope, and 512 KiB total; verify index byte metadata against the actual UTF-8 envelopes and reject corrupt/oversized/duplicate-context snapshots after restart without broad deletion of unrelated preferences
• fit large batches with a bounded newest-suffix pass rather than repeated aggregate serialization
• commit payload, LRU index, and evictions atomically; async writes are revision-fenced
• expose QRemoteConfigurationAssignmentType.FROZEN("frozen"), preserving UNKNOWN for future values

Verification

• ./gradlew :sdk:testDebugUnitTest :sdk:testReleaseUnitTest detektAll
• ./gradlew :sdk:assembleDebug :nocodes:assembleDebug :sample:assembleDebug
• identity/race, process-restart, corruption, eviction, oversize, parsing, response classification, and Moshi enum tests
• git diff --check

Release fence

Configurator type-3 writes remain disabled until this SDK and the corresponding Apple/Sandwich/wrapper releases are in the compatibility matrix.

[shameondev]

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