feat(ui): clear focus from textboxes on Escape in the main window

Mirrors the existing click-outside behavior. Scoped to MainWindow only
(not a generic TopLevel handler) so modal Escape-to-close bindings and
Mission Control's ConPTY tiles are unaffected.

src/ClaudeDo.Ui/CLAUDE.md

@@ -66,6 +66,7 @@ Modals use `TaskCompletionSource` results behind the reusable `ModalShell` contr
 - "Run Now" CanExecute re-evaluates when worker connection state changes
 - Icon gotcha: `PathIcon` fills geometry. Line-art/stroke icons must be defined as filled geometry or rendered as a stroked `Path` (e.g. `Icon.PlanDay` via the `Path.plan-icon` style); a pure stroke path used with `PathIcon` is invisible.
 - Window key bindings live on `MainWindow`: `Ctrl+K` focuses search, `Ctrl+N` the add-task box. Do **not** bind bare punctuation gestures — `OemQuestion` used to hold search focus and silently swallowed `#` app-wide on a German layout.
+- `FocusClearing` also clears focus from a TextBox on Escape, mirroring its click-outside behavior — but the KeyDown handler is scoped to `MainWindow` specifically (`AddClassHandler<MainWindow>`, not `<TopLevel>`). Modal windows (`AboutModalView` etc.) each bind their own `Window.KeyBindings` Escape → close; since modals are separate `Window` instances, this handler never runs there, so Escape still closes them unchanged. Mission Control's ConPTY tiles (`InteractiveTerminalView`) live in `MissionControlWindow`, also unaffected — Escape always reaches the PTY there.
 - `Ellipse.spinner` (IslandStyles) is the shared indeterminate spinner: used for a starting ConPTY pane (`InteractiveTerminalViewModel.IsStarting`) and in place of the refine button while `TaskRowViewModel.IsRefining`.
 - `ConPtyPaneViewModel` resolves its own launch spec (ctor takes a descriptor **factory**; the host wires handlers and then calls `Start()`), so the Mission Control tile appears immediately with its spinner while the worker is still preparing the worktree. A failed launch keeps the tile with its inline error banner instead of never appearing.
 - `SessionTerminalView` is the reusable log terminal (StyledProperties `Entries`, `Label`, `IsRunning`, `IsDone`, `IsFailed`) used for both the task `Log` and the prep `PrepLog`.