web/settings: rebuild the user settings screens from the redesign
Ports the desktop user-settings screens from the Settings Redesign
Figma (TFhrx7FBh2Ue5SGH8CUeBU) onto a shared set of primitives: a
sidebar Navigation matching the DS component's four Active x Hovered
states, plus header/toolbar/list/row/entry pieces and a drill-down
shell for the in-place sub-views.
Seven tabs and nine drill-downs. Keys keeps its existing
`tangled.publicKey` wiring and moves the add form from a popover to
/settings/keys/new; the rest are mocked, since nothing behind them
exists yet.
Three token pairs are new because the navigation aliases *invert*
between modes -- light recesses the frame and raises the active item,
dark does the opposite -- so they cannot be spelled with an existing
pair. Button gains per-variant disabled surfaces: Figma models
disabled as its own fill/text pair rather than a dimmed enabled state,
which is what the disabled Save and Add buttons in the designs need.
Tag grows the DS badge geometry as an additive `sm` size plus the
status colours, leaving its existing callers untouched.
Verified light and dark against the Figma renders; nav, card and
surface tokens plus nav/card geometry and heading size all match.
Refs TAN-575.
Signed-off-by: eti <eti@eti.tf>