[access-host-lifecycle] - Dispose access graph and verify end-to-end privacy

[JoshuaRowePhantom]

Part of #1507 and master #1505

Parent

• Direct parent: [access-host] - Track startup composition handoff and lifecycle slices #1507.
• Architecture master: [access-broker] - Unify credential-use authorization, acquisition, renewal, and presentation #1505.

Dependencies

• Depends on: [access-host-handoff] - Hand exact authorization rows instance to MainWindow #1563.
• Depends on: [access-host-threading] - Thread one broker through all production composition paths #1564.
• Depends on: [access-memory-ui] - Add release-memory list and Forget action #1554.
• Depends on: [access-cache-ui] - Add credential-cache list and Delete action #1555.
• Depends on: [access-provider-grant-ui] - Add provider-grant list and Revoke action #1556.

Summary

Implement final shutdown ordering and end-to-end migration/privacy assertions.

Current Limitation / Root Cause

No process owner currently shuts down UI actions, broker work, callbacks, listeners, processes, and stores in one deterministic sequence.

Affected Files

Path	Change
Phantom.Workspaces/Services/Access/AccessHostServices.cs	Implement the bounded production change owned by this issue.
Phantom.Workspaces/App.axaml.cs	Implement the bounded production change owned by this issue.
Phantom.Workspaces.Tests/Authorization/AuthorizationEndToEndTests.cs	Implement the bounded production change owned by this issue.
Focused test file	Add only the tests listed below.

Design / Fix

This slice implements the following exact contract:

public sealed class AccessHostServices : IAsyncDisposable
{
    public ValueTask DisposeAsync();
}

Disable UI, reject broker calls, cancel/tombstone work, dispose unpublished results, stop listeners/processes, clear registry, then dispose stores. Verify no superseded caller path remains.

Use required-init properties and named object initializers. The commit must build and its focused tests must pass without relying on a second implementation slice landing in the same commit.

Security and Privacy Invariants

• Release/use authorization occurs before material access or provider interaction whenever this slice can reach either boundary.
• No token, secret value, OAuth state, verifier, authorization URL, signed URL, device code, callback, account name, unsafe identifier, or credential-bearing result enters UI-safe state, logs, notifications, entities, or persistence.
• Typed results remain caller-owned and disposable; provider/cache artifacts remain executor-owned.
• Errors are typed and sanitized; no broad catch or success-shaped fallback is introduced.

Exclusions

• No batch API, compatibility bridge, legacy-data migration, silent interactive renewal, or unrelated provider work.
• No production types beyond the bounded files/classes named here.
• No UI work unless this issue is explicitly a UI slice.

Commit Plan

Commit 1 — [access-host-lifecycle] - Dispose access graph and verify end-to-end privacy

Production scope: Phantom.Workspaces/Services/Access/AccessHostServices.cs, Phantom.Workspaces/App.axaml.cs, Phantom.Workspaces.Tests/Authorization/AuthorizationEndToEndTests.cs.

Tests: AuthorizationEndToEndTests methods listed below.

Acceptance: one small coherent commit; no opportunistic adjacent migration.

Expected Tests

Test Name	Class	What It Verifies
AccessHostServices_DisposeAsync_CancelsStopsAndDisposesExactlyOnce	AuthorizationEndToEndTests	Verifies the named contract and leaves adjacent slices independently testable.
AuthorizationEndToEnd_LateCompletion_DoesNotCacheLaunchOrRecreateRows	AuthorizationEndToEndTests	Verifies the named contract and leaves adjacent slices independently testable.
AuthorizationEndToEnd_AllCredentialPaths_AreBrokeredAndSensitiveArtifactsRemainPrivate	AuthorizationEndToEndTests	Verifies the named contract and leaves adjacent slices independently testable.