[codex] redesign task card

[Kibnet]

What changed

• Redesigned the current task details card into a single structured card with command bar, header, description, planning, repeater, and relations sections.
• Preserved the existing Relations UX: four relation groups, Add buttons, inline editors, suggestions, confirm/cancel, and per-group trees.
• Added localized section labels and stable automation ids for the new card structure.
• Added Avalonia headless layout coverage for desktop and phone-width card rendering.
• Stabilized the deadline UI test helper and fixed the planned duration editor so stale uncommitted duration text does not remain visible after switching tasks.

Why

The old card was a linear stream of fields, which made the current task harder to scan and did not explicitly cover Android phone-width layout. The new structure makes primary task state, editing groups, and relations easier to find while keeping existing bindings and workflows intact.

User impact

Users get a clearer task card on desktop and a vertical, scrollable layout on narrow Android-sized screens without losing existing relation editing behavior.

Validation

• PASS dotnet test .\src\Unlimotion.Test\Unlimotion.Test.csproj -- --treenode-filter "/*/*/MainControlTaskCardLayoutUiTests/*" --no-progress
• PASS dotnet test .\src\Unlimotion.Test\Unlimotion.Test.csproj -- --treenode-filter "/*/*/MainControlNewTaskDeadlineUiTests/*" --no-progress
• PASS dotnet run --project .\tests\Unlimotion.UiTests.Headless\Unlimotion.UiTests.Headless.csproj -- --treenode-filter "/*/*/MainWindowHeadlessTests/*" --no-progress
• PASS dotnet build .\src\Unlimotion.Desktop\Unlimotion.Desktop.csproj
• PASS dotnet build .\src\Unlimotion.Test\Unlimotion.Test.csproj
• BLOCKED dotnet build .\src\Unlimotion.Android\Unlimotion.Android.csproj: local SDK reports missing workload wasm-tools (NETSDK1147).