feat(windows): integrate beta.9 desktop runtime

[devswha]

Summary

• Merge main into the Windows preview branch without rewriting history; preserve Windows Job ownership and Linux/macOS origin, lifecycle, launcher and QA-profile contracts.
• Keep package 2.0.0-beta.9, desktop 0.2.3, SDK/native 0.16.4, Bun 1.4.0 and bundled Windows Node 22.22.2 unchanged.
• Own embedded SDK Settings and managers: supported sdkHostModeSupported: false, runtime-only delegated model roles, strict flushOrThrow(), exact construction-failure ownership, and cleanup poisoning.
• Keep complete Windows SDK/delegation coverage. Isolate the native file-lock contract in its own Bun process; retain fixture stores and roots when session disposal is unconfirmed instead of racing live teardown.
• No private SDK imports, dependency patches, deletion retries, indefinite disposal waits, antivirus exclusions, weakened assertions or new Windows skips.

Blocking SDK finding

At 11bee00, Windows run 34056951959 reproduced the failure without creating any AgentSession. On Windows build 10.0.20348, snapshotDirectoryTree succeeds but public native exactRemoveDirectoryTree returns {ok:false,code:"sharing_violation",detachedPath:<original lock path>}. Native removal, SDK release and concurrent SDK release all fail on both C: temporary and D: checkout paths. The same six cases pass on local Windows 11 build 10.0.26200. The handle holder is not established; no antivirus attribution is made.

This isolates the pinned SDK/native filesystem release path, not an app broker or SessionManager. Both packages' latest published version is still 0.16.4. The dependency-change prohibition remains in effect; no SDK workaround has been applied.

Commit-scoped verification

• 6edef4a: Linux Node 22/24 full verify 34054572060, archive 34054572042, desktop 34054572039 all passed, including Ubuntu 22.04/24.04 packaged server and GUI checks.
• 6edef4a: Windows PR 34054572083 and push 34054569808 attempt 2 passed compiler/source/tooling, Rust core, NSIS build, desktop lifecycle, staging, silent Unicode-path installation and installed payload smoke. Node runtime: 126 passed / 3 existing skips. Full Bun lane: 93 passed / 1 existing skip / 25 failed in both runs. Runtime failure correctly blocked installer upload.
• 11bee00: six standalone native/SDK probe cases and 53 Windows script tests passed locally; ESLint and diff checks passed. Windows reproduced the isolated native failure above; the unchanged full Bun lane remained enabled and reported 93/1/25.
• 3a9506f: complete local delegation suite 32 passed / 0 failed; focused disposal/flush-failure regressions, typecheck, ESLint and diff checks passed. Current Actions results remain pending; this test-only ownership guard is not a fix for native lock removal.
• Earlier b2e134c/6edef4a local evidence: three two-CPU/cross-volume SDK runs each 85 passed / 1 skip, combined SDK/delegation 116 passed / 1 skip, five later manager/flush regressions, four manifest checks and client/server builds passed. Local native-core checks remain unavailable without dist-native/gajae-core.exe.

Acceptance boundary

Draft PR, not a release; no main-branch merge is authorized. Current Windows runtime is blocked by the pinned native SDK failure. Installer construction and silent installed-backend smoke do not establish interactive GUI/login, a real paid-provider turn, deep-link, reinstall/uninstall or signing acceptance. Historical beta.8 evidence remains separately scoped in docs/WINDOWS-DESKTOP.md.

[devswha]

Implementation is paused at the owner's request; the SDK source/dependency scope expansion was not approved.

The durable Windows handoff is committed and pushed in 044fe8d: docs/V2-SESSION-HANDOFF.md. It records the 3a9506f source/test state, isolated native SDK failure, exact CI evidence, safety constraints and remaining installer/interactive acceptance.

This PR remains draft and release-blocked. Further implementation requires a new owner instruction; no SDK patch, dependency change, gate bypass or release was performed.