feat: log memory warnings instrumentation

[mario-launchdarkly]

• add sample for memory and cpu stress to example app

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Note

Add memory warning auto-instrumentation that logs pressure events and integrate new CPU/memory stress tools and navigation in the Example app.

• Observability (SDK):
  • Add Options.AutoInstrumented.memoryWarnings and semantic attr SemanticConvention.systemMemoryWarning.
  • Introduce MemoryPressureMonitor auto-instrumentation to log warning/critical memory pressure events.
  • Wire MemoryPressureMonitor in ObservabilityClientFactory when logs are enabled and autoInstrumentation includes .memoryWarnings.
• Example App:
  • Enable .memoryWarnings in Client config.
  • Add stress tools: CpuLoadGenerator, MemoryPressurizer, and SystemUnderPressureView with navigation (Path.stressSamples) and UI entry point.
  • Switch to @EnvironmentObject/@StateObject for Browser and update navigation wiring.
• Project:
  • Set iOS deployment target to 16.6 for the app target.

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