Keep list navigation stable and preserve terminal failure diagnostics

[harder]

Repeated navigation past list endpoints lets Terminal.Gui keys reach parent focus handlers; dialog lists can move focus to action buttons. Scout's j/k and filter-input cursor changes also selected rows without scrolling them into view, and Home/End used column movement despite the row-navigation help.

This keeps endpoint navigation in package tables and related dialog lists while preserving Tab, scrolls programmatic cursor moves, maps Home/End to table start/end, and permits an empty version picker. Direct window disposal now stops UI callback admission before child disposal. Cancellation callback failures are retained, and startup/run/shutdown/disposal exceptions keep their stack traces and inner exceptions, printed after independent terminal cleanup attempts.

Validation:

• Verified Terminal.Gui 2.5.1-develop.44 against its recorded upstream source commit. No AGENTS.md exists in this checkout or its parent directories; followed CONTRIBUTING and CI gates.
• 365 Release tests passed, including 47 new cases using the actual application keyboard/event pipeline and failure injection.
• Locked restore and both Release application builds passed with no warnings/errors.
• Portable and Identity Native AOT publishes/mock smokes passed for Windows ARM64 and x64, with required companion files verified.
• Live Windows ConPTY checks used mock data and the production window with 80 harmless rows: repeated endpoints, aliases, paging, Tab, filtering, sorting, refresh, source widening, and 140×32/100×24 resize. Separate actual run-loop plus child-disposal failures exited with code 1, retained full diagnostics, and restored terminal modes.
• Dependency-monitor test, site build, and whitespace check passed.

Widening source/local filters and late inventory/detail responses passed without additional production fixes. The reported macOS crash and leaked mouse escape codes were not reproduced; macOS/Linux interactive validation was not run.

[Copilot]

🟢 Approval recommended

The implementation is internally consistent and its lifecycle and interactive navigation behavior are covered by focused regression tests.

0 open findings

What changed in this PR

Improves Terminal.Gui navigation stability and ensures lifecycle failures retain complete diagnostics after terminal cleanup.

Changes:

• Keeps list navigation focused and visible at endpoints.
• Adds orderly shutdown, disposal, and exception reporting.
• Adds comprehensive navigation and lifecycle regression tests.

File	Description
Program.cs	Uses centralized application lifecycle handling.
src/​App.cs	Stabilizes navigation, scrolling, cancellation, and disposal.
src/​ApplicationLifetime.cs	Coordinates startup, shutdown, cleanup, and diagnostics.
src/​BackgroundTaskTracker.cs	Exposes failure recording for cancellation errors.
src/​PackageListView.cs	Prevents endpoint navigation from escaping lists.
src/​Ui.cs	Supports empty version lists safely.
src/​WorkflowDialogs.cs	Applies stable navigation to dialog lists.
tests/​ApplicationLifetimeTests.cs	Tests independent cleanup and diagnostic preservation.
tests/​ListNavigationTests.cs	Tests navigation, filtering, refresh races, and callbacks.
docs/​architecture.md	Documents lifecycle ownership and cleanup behavior.

🧠 Review effort: Balanced

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