Drop mission-image ring border; reskin Login hover (no glow)

- The animated SVG already draws its own hairline frame + corner
  brackets at the viewBox edge. Remove the `box-shadow: 0 0 0 1px`
  ring (in both the base `.mission-image` rule and the
  desktop-min-1025px `.mission-screen .mission-image` override) so
  the image isn't double-framed. Drop-shadow for elevation kept.
- Replace the Login button hover effect. The amber drop-shadow halo
  used the same visual language as the active Mission/MAKIMA nav
  buttons (which also glow amber underneath); on hover Login now
  inverts to a deep-night background with amber ink and a hairline
  ::after rule that slides in from the left along the top edge —
  reads as 'armed' rather than 'glowing'. Letter-spacing widens
  slightly on hover (0.18em → 0.22em) for a subtle ink-spread.
  Added :active and :focus-visible states for keyboard a11y.

0 files changed, 0 insertions, 0 deletions