dsh-welcome-back v0.2.2

Safe UI usability update for DSH Desktop.\n\n- Keeps the known-good DSH client inject list unchanged\n- Moves the floating ◷ button to the bottom-left by default\n- Supports drag-to-position and a right-click menu\n- Provides Ctrl+Shift+Alt+W as a recovery shortcut after hiding the floating button\n- Limits and scrolls long checkpoint text while keeping A/B/C/D visible\n\nThis release deliberately does not register a DSH Settings page after the v0.3.0 renderer-startup regression. Declared compatibility: >=0.2.0-rc.2 <0.2.1.