feat: Introduce Phase 5 features for EasyAppDev.Blazor.Store

- Added comprehensive documentation for Phase 5: Killer Features, outlining enhancements in data fetching, mutable syntax, DevTools integration, and server-side state synchronization.
- Implemented IStateValidator interface for custom state validation, including NoOpStateValidator and CompositeStateValidator.
- Developed MessageSigner class for HMAC-based message signing to secure cross-tab and cross-origin communication.
- Created SecurityOptions class to manage state validation and sensitive data filtering configurations.
- Added SensitiveDataFilter for JSON serialization to prevent exposure of sensitive information.

Author: mashrulhaque

docs/API_DESIGN_GUIDELINES.md

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+# EasyAppDev.Blazor.Store Roadmap
+
+> The path from solid foundation to killer library
+
+## Current State Assessment
+
+**Version:** 3.0.0
+**Status:** Production-ready, actively maintained
+**Rating:** 9/10 - Feature-complete, production-ready with killer features
+
+### What We Have
+- Zustand-inspired simplicity for Blazor
+- Immutable state via C# records
+- Thread-safe async-first updates
+- Middleware pipeline (DevTools, Persistence, Logging)
+- Selector-based granular subscriptions
+- Async action state machine (AsyncData<T>)
+- Debounce/Throttle/LazyCache utilities
+
+### What's Been Added (Phase 4 & 5)
+- Optimistic updates with rollback
+- Undo/redo with history
+- Type-safe actions
+- Source generators
+- TanStack Query-style data fetching
+- Immer-style mutable syntax
+- Enhanced DevTools with time-travel
+- Plugin ecosystem
+- Server-side state sync
+
+---
+
+## Vision
+
+**Goal:** Become the go-to state management library for Blazor - the one developers *want* to use, not the one they're forced to use.
+
+**Philosophy:** Simple, Type-Safe, Pleasant
+
+**Differentiators:**
+1. Simplicity of Zustand
+2. Type-safety of C#
+3. Developer experience that doesn't make you hate your life
+
+---
+
+## Phase Overview
+
+| Phase | Version | Focus | Status |
+|-------|---------|-------|--------|
+| [Phase 1](phases/PHASE_1_BUG_FIXES.md) | 1.1.x | Bug Fixes & Polish | 🟢 Complete |
+| [Phase 2](phases/PHASE_2_CLEANUP.md) | 1.2.x | Cleanup & Simplification | 🟢 Complete |
+| [Phase 3](phases/PHASE_3_CORE_ENHANCEMENTS.md) | 2.0.0 | Core Enhancements | 🟢 Complete |
+| [Phase 4](phases/PHASE_4_ADVANCED_FEATURES.md) | 2.x | Advanced Features | 🟢 Complete |
+| [Phase 5](phases/PHASE_5_KILLER_FEATURES.md) | 3.0.0 | Killer Features | 🟢 Complete |
+
+---
+
+## Quick Links
+
+### Planning Documents
+- [Phase 1: Bug Fixes & Polish](phases/PHASE_1_BUG_FIXES.md)
+- [Phase 2: Cleanup & Simplification](phases/PHASE_2_CLEANUP.md)
+- [Phase 3: Core Enhancements](phases/PHASE_3_CORE_ENHANCEMENTS.md)
+- [Phase 4: Advanced Features](phases/PHASE_4_ADVANCED_FEATURES.md)
+- [Phase 5: Killer Features](phases/PHASE_5_KILLER_FEATURES.md)
+
+### Reference Documents
+- [Architecture](ARCHITECTURE.md)
+- [Design Principles](DESIGN_PRINCIPLES.md)
+- [Coding Standards](CODING_STANDARDS.md)
+- [API Design Guidelines](API_DESIGN_GUIDELINES.md)
+- [Testing Strategy](TESTING_STRATEGY.md)
+
+---
+
+## Phase 1: Bug Fixes & Polish (v1.1.x)
+
+**Goal:** Fix known issues without breaking changes
+
+### Key Deliverables
+- [x] Convert `AsyncData<T>` from class to record
+- [x] Add thread-safety to `MemoizedSelector<T>`
+- [x] Replace swallowed exceptions with proper logging
+- [x] Replace `Console.WriteLine` with `ILogger`
+- [x] Add XML documentation to all public APIs
+
+**Breaking Changes:** None
+**Risk Level:** Low
+
+[Full Details →](phases/PHASE_1_BUG_FIXES.md)
+
+---
+
+## Phase 2: Cleanup & Simplification (v1.2.x)
+
+**Goal:** Reduce complexity, improve maintainability
+
+### Key Deliverables
+- [x] Remove deprecated `Update()` method from Store, IStateWriter, and StoreComponent
+- [x] Extract diagnostics to separate package (deferred - using #if DEBUG conditional compilation)
+- [x] Consolidate DevTools overloads to single IServiceProvider method
+- [x] Slim down `StoreComponent<T>` - created `StoreComponentWithUtilities<T>`
+- [x] Add `UpdateWithAsync` extension method for simplified async patterns
+
+**Breaking Changes:** Minor (deprecated APIs removed)
+**Risk Level:** Low-Medium
+
+[Full Details →](phases/PHASE_2_CLEANUP.md)
+
+---
+
+## Phase 3: Core Enhancements (v2.0.0)
+
+**Goal:** Add foundational features that enable advanced patterns
+
+### Key Deliverables
+- [x] ISelector subscription on IStore - Subscribe using memoized selectors
+- [x] Functional middleware syntax - Use/UseWhen/UseForAction inline middleware
+- [x] MiddlewareContext - Rich context for middleware with phase info and services
+- [x] Improved PersistenceOptions API - Callbacks, transforms, and fine-grained control
+- [x] Structured error boundaries - StoreError record with ErrorLocation enum
+- [x] OnError handler in StoreBuilder - Centralized error management
+
+**Breaking Changes:** Yes (major version bump)
+**Risk Level:** Medium
+
+[Full Details →](phases/PHASE_3_CORE_ENHANCEMENTS.md)
+
+---
+
+## Phase 4: Advanced Features (v2.1.0)
+
+**Goal:** Add powerful features for complex applications
+
+### Key Deliverables
+- [x] Optimistic updates with rollback - `UpdateOptimistic`, `UpdateOptimisticWithConfirm`
+- [x] Built-in undo/redo - `IStoreHistory<T>` with `UndoAsync`/`RedoAsync`
+- [x] Type-safe actions/events - `IAction`, `IActionDispatcher<T>`, reducer pattern
+- [x] Cross-tab state sync - `WithTabSync` middleware using BroadcastChannel API
+- [x] Source generators for boilerplate - `[Store]` attribute generates setters/actions
+
+**Breaking Changes:** Additive only
+**Risk Level:** Medium
+
+[Full Details →](phases/PHASE_4_ADVANCED_FEATURES.md)
+
+---
+
+## Phase 5: Killer Features (v3.0.0)
+
+**Goal:** Become the undisputed best Blazor state library
+
+### Key Deliverables
+- [x] TanStack Query-style data fetching - UseQuery, UseMutation, QueryClient
+- [x] Immer-style mutable syntax - Produce() with Draft pattern
+- [x] Full DevTools time-travel debugging - Enhanced middleware with action replay
+- [x] Plugin ecosystem - IStorePlugin, PluginHost, built-in plugins
+- [x] Server-side state sync - SignalR-based real-time sync with presence
+- [ ] Visual Studio / Rider tooling (Future enhancement)
+
+**Breaking Changes:** None (additive)
+**Risk Level:** Medium (well-tested)
+
+[Full Details →](phases/PHASE_5_KILLER_FEATURES.md)
+
+---
+
+## Success Metrics
+
+### Adoption
+- GitHub stars growth
+- NuGet download trends
+- Community contributions
+- Stack Overflow questions
+
+### Quality
+- Test coverage > 90%
+- Zero critical bugs in production
+- Documentation completeness
+- API stability
+
+### Developer Experience
+- Time to first working app < 5 minutes
+- Learning curve feedback
+- Migration ease from other libraries
+
+---
+
+## Principles Guiding Development
+
+1. **Simplicity over features** - Don't add complexity unless it solves real problems
+2. **Immutability is non-negotiable** - Every API must preserve immutability
+3. **Type-safety first** - Leverage C# compiler, no magic strings
+4. **Async by default** - Synchronous is the exception
+5. **Fail gracefully** - Never crash the app for optional features
+6. **Test everything** - If it's not tested, it's broken
+
+---
+
+## Contributing
+
+See each phase document for specific contribution opportunities. Priority areas:
+- Bug fixes (Phase 1)
+- Documentation improvements
+- Test coverage expansion
+- Sample applications
+
+---
+
+## Changelog
+
+| Date | Update |
+|------|--------|
+| 2025-12-01 | Phase 5 completed - v3.0.0 released (Query system, Immer syntax, Enhanced DevTools, Plugins, Server sync) |
+| 2025-12-01 | Phase 4 completed - v2.1.0 released (Optimistic updates, Undo/Redo, Actions, TabSync, Source Generators) |
+| 2025-12-01 | Phase 3 completed - v2.0.0 released |
+| 2025-12-01 | Phase 2 completed - v1.2.0 released |
+| 2025-12-01 | Phase 1 completed - v1.1.0 released |
+| 2024-12-01 | Initial roadmap created |
+
+---
+
+*This roadmap is a living document. It will evolve based on community feedback, real-world usage patterns, and the Blazor ecosystem evolution.*