docs: Split unified renderer_guide.md into core_sdk_spec.md and framework_adapter_spec.md for v0.9.1 and v1.0

[jacobsimionato]

Description of Changes

This Pull Request splits the unified, single-file renderer_guide.md into two highly focused specifications across both version v0.9.1 and v1.0 folders:

1. core_sdk_spec.md (Framework-Agnostic Layer / Core SDK): Contains all agnostic definitions including:
   • Event and Stateful Stream (Signals) specifications.
   • Core state models (SurfaceGroupModel, SurfaceModel, SurfaceComponentsModel, ComponentModel, DataModel with bubble/cascade pointers, and type-coercion table).
   • Reactive dynamic bindings, contexts (ComponentContext, DataContext), capability schema-tagging/reference-generation rules, and MessageProcessor.
   • Core catalog APIs (FunctionApi, FunctionImplementation, Catalog), core-side standard Basic Catalog signatures, and expression evaluation logic (formatString).
   • Unified Core SDK implementation roadmap/phases for autonomous agents.
2. framework_adapter_spec.md (Framework-Specific / View Layer): Contains all visual, native-framework specifications including:
   • Concrete renderer interfaces (ComponentImplementation functional/stateful methods, ComponentInstance, and Surface root views).
   • Component rendering strategies (direct, pre-bound binders, and TypeScript generic binders).
   • Lifecycle rules (lazy subscription, path stability, unmount cleanup, ownership rules, structural vs data props, and context propagation).
   • Interactive validation (Checkable traits) and visual catalogue overrides.
   • Comprehensive three-column UX layout and integration testing requirements for the standard Gallery App.
   • Renderer-specific implementation roadmap/phases for autonomous agents.

Additionally, the workspace navigation instructions in .agents/skills/a2ui-sdk-design/SKILL.md have been fully updated to reference the newly split files.

Rationale

Separating the core data model and state logic from the UI rendering layer provides several key architectural advantages:

• Headless & Server Compatibility: Empowering server-side or headless languages (where there are no UI/view adapters) to implement the Core SDK identically and safely.
• Architectural Clarity: Defining a strict, clean, one-way dependency boundary from Framework Adapters to the Core SDK.
• Improved Code Reuse: Allowing core schemas and state subscription layers to be shared seamlessly across multiple visual adaptors (e.g. sharing web_core binders between React and Angular renderers).
• Maintenance & Extension: Isolating layout and styling rules from critical serialization and validation logic.

Testing/Running Instructions

Reviewers can verify the changes by doing the following:

1. File Verification: Confirm that the files specification/v0_9_1/docs/core_sdk_spec.md, specification/v0_9_1/docs/framework_adapter_spec.md, specification/v1_0/docs/core_sdk_spec.md, and specification/v1_0/docs/framework_adapter_spec.md exist and that the old renderer_guide.md files have been correctly deleted.
2. Prettier Verification: Run Prettier formatting to ensure syntax and structure are aligned:

   ./scripts/fix_format.sh

3. Reference Verification: Inspect .agents/skills/a2ui-sdk-design/SKILL.md to confirm the navigation points correctly to the split specs.

[gemini-code-assist]

Code Review

This pull request introduces a major restructuring of the A2UI documentation by splitting the architecture into a 'Core SDK Specification' and a 'Framework Adapter Specification'. It updates the documentation to reflect these changes, including updated agent implementation guides and cross-references. The review comments identified several broken path references in the documentation that pointed to the wrong version directory (v0_9 instead of v0_9_1). These have been noted for correction.

[gemini-code-assist]

The path reference uses v0_9 instead of v0_9_1. Since this file is located under the specification/v0_9_1/ directory, all references to the specification paths in this section (including lines 517–520) should be updated to use v0_9_1 to ensure consistency and prevent broken links.

Suggested change

	- `specification/v0_9/docs/basic_catalog_implementation_guide.md` (for functional specs and spacing rules for when you get to the basic catalog)
	- specification/v0_9_1/docs/basic_catalog_implementation_guide.md (for functional specs and spacing rules for when you get to the basic catalog)

[gemini-code-assist]

The path reference uses v0_9 instead of v0_9_1. Since this specification is for version v0.9.1 and resides in the specification/v0_9_1/ directory, the path should be updated to point to v0_9_1.

Suggested change

	- `specification/v0_9/docs/basic_catalog_implementation_guide.md` (for rendering, typography, alignment, and spacing rules).
	- specification/v0_9_1/docs/basic_catalog_implementation_guide.md (for rendering, typography, alignment, and spacing rules).

[gemini-code-assist]

The path reference uses v0_9 instead of v0_9_1. Update the path to use v0_9_1 to match the correct directory structure for this version.

Suggested change

	- Load JSON samples from `specification/v0_9/json/catalogs/minimal/examples/`.
	- Load JSON samples from specification/v0_9_1/json/catalogs/minimal/examples/.

[gemini-code-assist]

The path reference uses v0_9 instead of v0_9_1. Update the path to use v0_9_1 to match the correct directory structure for this version.

Suggested change

	- Update the Gallery App to load samples from `specification/v0_9/json/catalogs/basic/examples/`.
	- Update the Gallery App to load samples from specification/v0_9_1/json/catalogs/basic/examples/.