docs(agents): plan W4 Windows application shell

[blakinio]

Purpose

Accept one bounded W4 launch plan for a Windows blank-window application-shell spike after completed W3.

Live state

• base main: e7b251c2b898ad76655ed71c72e72c1e26f9364f
• W1/W2/W3 completed and archived
• open PRs feat(ui): prototype Oteryn login shell #23/fix(assets): select release archives by client version #37 are legacy-only; ci: prove official Tibia login without OCR on Synology #48 is isolated operational work
• no active Rust task or PR owns apps/client, Cargo/lockfile integration or the application-shell contract

Candidate dependency

Primary-source revalidation still identifies exact winit 0.30.13 (Apache-2.0, MSRV 1.70). Selection remains confined to the implementation worker and exact cargo-deny result.

Delivered plan

• exactly one implementation worker W4-SHELL;
• one unique Cargo/lockfile/dependency-policy/shared-document lease;
• one application package only, category app;
• exact worker prompt NEXT_WINDOWS_SHELL_AGENT.md;
• explicit automated-versus-interactive Windows evidence policy;
• W1-W3 relaunch remains prohibited.

Boundaries

No implementation in this coordination PR. No renderer/GPU, protocol, identity, assets, audio, feature UI, persistence, async runtime, direct Win32 or external-repository changes.

Task

OTC-20260729-plan-w4-windows-shell

Validation

Exact final head: bb734c1d1c93dc8302d67a971166a2feedaae510.

• live overlap/base/dependency preflight passed;
• complete five-file path/content review passed;
• exact-head required CI pending.