touch-indication-bounds-and-alpha

Soften an app-wide touch ripple by alpha alone and give it the right bounds — the colour derives from the local content colour and stays correct inside a forced-scheme subtree, while pinning one paints darker than a near-black surface. Covers why the theme's configuration reaches a bare Modifier.clickable, why .clip(shape) must come before .clickable, why a card and its clip need one shape value, why two clickable…