refactor(windows): start experimental application/controller layer

[Dailin521]

Goal

Start Phase 1 with a UI-independent Application/controller seam that is exercised by the real Windows GUI.

This replaces #62's docs-first stable JSONL v1/UI-probe proposal with an experimental 0.x architecture. No public protocol or compatibility contract is introduced here.

What changed

• add cross-platform CodexProviderSync.Application and focused controller tests
• use typed snapshots, commands, provider state, model modes, validation, and immutable sync/switch requests
• route WinForms initialization/refresh, Provider selection, model choices, and sync/switch request mapping through the controller
• freeze execution inputs before any await, preventing model/provider drift while an operation is running
• fall back to the current Provider when a saved selection no longer exists
• reject concurrent controller operations and build each request from one atomic snapshot
• block Execute/Restore after a failed refresh, especially when the user changed Codex Home
• run Application tests in CI and the Release build
• document the non-normative automation direction in docs/AUTOMATION_DESIGN_NOTES.md

Explicitly out of scope

• an Automation executable
• JSONL, a published schema, or stable v1 fields/error codes
• plan IDs or a plan/execute protocol
• a UI inspect/capture probe
• release packaging changes
• macOS GUI migration
• restore/prune controller migration

Verification

• npm test — 110/110
• node scripts/verify-release-version.js --tag v0.3.2
• git diff --check
• independent static review with no remaining blockers
• Windows/macOS .NET CI — run #132
• manual Windows smoke check of refresh, Provider selection, sync, and switch

The first CI attempt exposed a namespace collision in Program.cs; commit b4308ee fixes it by explicitly qualifying the WinForms Application type. The full rerun is green.

This remains Draft until the manual Windows smoke check is complete.

[Dailin521]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Chef's kiss.

Reviewed commit: b4308ee73d

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[Dailin521]

Superseded by the completed v0.4 integration in #71, which preserves and extends this Application/Controller baseline. Closing this Draft without merging.