docs: define AI automation interface and Windows GUI contract

[Dailin521]

Summary

• define the stable JSONL v1 contract for the planned Windows Automation companion executable
• document the shared Application/Controller architecture for WinForms, Automation, and future macOS migration
• add a mandatory Windows GUI development contract covering state ownership, stable control IDs, layout, accessibility, write safety, and testing
• link both documents from AGENTS.md and clearly mark the Automation executable as not implemented yet

Why

The current WinForms application mixes UI state and business behavior, while GUI verification relies heavily on local desktop interaction and private-field reflection. These documents establish the agreed structure for AI-callable state/behavior testing, internal WinForms screenshots, guarded real writes, and future Windows development.

Impact

Documentation only. This PR does not add the Automation executable or change runtime behavior. Implementation will continue incrementally on this branch/PR.

Validation

• git diff --check
• reviewed branch scope and confirmed the worktree was clean
• code tests were not run because this commit changes Markdown only

[Dailin521]

Thanks for documenting the original direction. We are no longer proceeding with this Draft as a stable JSONL v1 and UI-probe contract.

The replacement starts from current main with a smaller Phase 1: extract an Application/controller layer, exercise it through WinForms, and require behavioral equivalence. Any later automation host will remain experimental during 0.x development until real controller usage establishes the compatibility surface. A UI probe will be evaluated separately.

Replacement: #70

Closing this PR as superseded. Its discussion remains available for historical context, but the proposed stable v1 contracts will not be merged.