[mdspinali]

React Native 0.82.1 iOS builds fail with fmt 11.0.2 on Xcode 27. This change adds the upstream fmt 12.1.0 backport and lowers the RN minimum to 0.82.1. The supported RN range is >=0.82.1 <0.84.0. RN 0.82.1 applications must apply the documented patch to their own RN dependency.

The change also includes the approved native migration, cursor, and historical replay repairs. The shared schema scenario verifies these repairs through Swift, Kotlin, and both RN bridges. The candidate is 0.4.0-rc.2, with iOS 17 as the Apple minimum. Existing dev changes, including #300, remain preserved.

Validation uses clean commits and preserved structured results. SDK inputs are unchanged between e2c3024380e288a65efdf2f9cbae27b7aefe87c0 and cfdd99f7e3037c3efc7a0e6dfab7815d3bf8e666.
Server and conformance inputs are unchanged between b536bbf94a125d58629a7532975342c93b733a5b and that final commit.

Check	Source	Result
make ci-source-quality	cfdd99f7	Passed. Kotlin: 748 tests. RN unit: 269 tests. Zero failures, errors, or skips.
Configured Trivy scan	cfdd99f7	Passed with zero findings. Policy unchanged.
make ci-candidate-server	b536bbf9	Passed in 5083 seconds. Rust: 435 tests. Normal Go results: zero failures or skips. Seven detected mutants, zero survivors.
make test-consumer-server	b536bbf9	Passed on Ubuntu 24.04 x86_64 with PostgreSQL 18.3.
Focused readiness mutation control	b536bbf9	Passed. The deliberate defect failed the required semantic assertion. Normal baselines passed before and after.
make ci-candidate-swift	e2c30243	Passed. Native results: 393 tests. Complete authored corpus: 15 tests.
make ci-candidate-kotlin	e2c30243	Passed. Instrumentation: 8 tests. Integration: 44 tests. Complete corpus: 16 tests.
make ci-candidate-rn-android	e2c30243	Passed. Smoke: 27 tests. Bridge: 16 tests. Complete corpus: 27 tests.
make ci-candidate-rn-ios	e2c30243	Passed. Smoke: 27 tests. Bridge: 11 tests. Complete corpus: 27 tests.
Four Mac support cells	e2c30243	Passed on iOS 17 and iOS 27. Both RN versions passed on iOS 27.
Four Android support cells	cfdd99f7	Passed on API 24 and API 37. Both RN versions passed on API 37.
Emulator archive tests	cfdd99f7	89 passed. The demonstrated cache replacement mutant failed the required assertion.

Both RN versions built through the native bridge on both platforms. Each support cell verified connect, push, pull, process termination, and durable resume. Independent source review included deletion and simplification checks.

Evidence records: Mac cells, Android cells, source quality and audits, server, and emulator archive control.

Earlier candidate helper fixture restarts failed after completed SDK phases. Their failures remain recorded. Separate fresh fixtures passed all eight support cells. No registry activation check was weakened.

The full package-manager audits still fail for upstream dependency findings tracked in #312, #328, #330, and #319. No advisory suppression, unsupported major override, or release exception was added. These issues block publication. The local support-cell results do not certify sealed release packages.

Related issues: #303, #331, #298, #329, #214.

This pull request targets dev. Master, release tags, and published packages remain unchanged.