Remove unnecessary type assertions across codebase

Add oxlint-tsgolint and configure typescript/no-unnecessary-type-assertion
to flag redundant `!` and `as Foo` casts. Type-aware mode is left off by
default to keep `npm run lint` fast; the rule sits configured for when we
turn type-aware on intentionally. Auto-fix removed ~283 redundant casts;
two manual touch-ups: a real tsgolint false positive in split-container.tsx
and a stale ChildProcess import after a double-cast collapsed.

packages/desktop/src/daemon/quit-lifecycle.ts

@@ -22,7 +22,7 @@ export interface StopOnQuitDeps {
 }
 
 export function shouldStopDesktopManagedDaemonOnQuit(settings: QuitLifecycleSettings): boolean {
-  return settings.daemon.keepRunningAfterQuit === false;
+  return !settings.daemon.keepRunningAfterQuit;
 }
 
 export async function stopDesktopManagedDaemonOnQuitIfNeeded(