Polish owl login after design review; add DESIGN.md

Fixes from the finish review of the natural owl:
- thinner glasses frames, closer to the user's reference owl
- smile-eyes on success instead of flat half-lids
- the page no longer shifts when an error appears; the card grows down
- invalid field keeps a red outline while focused
- stars stay clear of the title, owl and card
- softer ear tufts, warm glow under the owl, larger owl on desktop

DESIGN.md and .impeccable/design.json record the shipped system.
The surface brief records the seed reference.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.impeccable/surfaces/src-ui-login-html.md

@@ -19,6 +19,6 @@ STORY: The ops user sees the owl, types the G2 password, and the owl's eyes foll
 
 FIRST VIEWPORT: Centered column. Product name "Charge Billed Automation", then the card with the owl perched on its top edge (feet on the border), password field with show/hide, full-width pill Sign in. The night sky fills the viewport.
 
-FORM: Pinned by the user (owl screenshot); no roll was run. seed: none (user-pinned direction)
+FORM: The user's pinned owl world (their screenshot, then "be natural", not game-like) governs; the roll was run for the record and does not override it. seed:60012e4e290e73f6
 
 FINISH: unreviewed and undocumented is unfinished; this build ends with the finish review, the verdict, DESIGN.md, and every shipping raster carrying its provenance