Harden observation architecture, examples, and documentation

[sonmbol]

Summary

• adds field-level SwiftUI Observation dependencies while preserving all 1.1 consumer APIs
• coalesces dependency-specific invalidations without duplicating Kotlin business state
• hardens cancellation, rebinding, shared collection, and actor delivery behavior
• adds Swift 5.9–6.2 package-manifest compatibility and drift validation
• expands DailyPulse into production-style presentation views and deterministic previews
• refreshes benchmarks, DocC, README architecture guidance, simulator media, and onboarding

Why

KMPObservableBridge should preserve Kotlin as the authoritative state owner while matching SwiftUI dependency, identity, and lifetime semantics as closely as imported Kotlin types allow. This release improves rendering granularity and evidence without changing the existing macro or property-wrapper APIs.

Compatibility

Existing 1.1 source remains compatible. Explicit macro fields remain required. iOS 17+ gains field-level Observation tracking; iOS 15/16 retain the correct global ObservableObject fallback.

Validation

• 41 Swift package tests
• strict concurrency with warnings as errors
• macro expansion coverage
• API compatibility against 1.1.0
• package-manifest consistency
• SKIE/native isolation audit
• package parsing and whitespace validation