nitr v0.10.1

Added

• A dark/light theme toggle on every page, including the login screen. The
  toggle introduced in v0.10.0 lived only in the panel's navbar, which is
  behind authentication — so the login screen could only follow the operating
  system's prefers-color-scheme and offered no way to override it. There is
  now a toggle on / (login), /panel, /docs and /password, so the theme
  can be changed before signing in and does not disappear when navigating away
  from the panel. The choice is stored in localStorage under nitr-theme and
  is applied by the existing pre-paint boot script, so it persists across
  reloads and sign-in without a flash of the wrong theme.
• The toggle now shows a moon while in light mode and a sun while in dark
  mode — the theme it will switch to, so it reads as an action rather than
  a status. Both are inline SVGs using currentColor and are swapped in CSS
  off the same data-theme attribute the boot script sets, so the correct icon
  is painted immediately with no JavaScript needed to initialise it. This
  replaces the half-filled-circle glyph v0.10.0 shipped.