fix: LIGHT variant bg animations, decoration grid spacing, bug doc updates

- chatBackground.ts: remove animRainGlowKeyframe and animGridBrightnessKeyframe
  from LIGHT anim-rain and anim-pulse definitions (these were removed from the
  import and from DARK variants in the previous session but the LIGHT variants
  were missed, leaving stale references that would cause a build error)
- ProfileDecoration.tsx: increase decoration grid gap 20→36 (visual gap was
  only 4px due to 8px image overflow beyond each 52×52 button), fix paddingBottom
  4→8 and add paddingRight:8 to prevent edge clipping
- LOTUS_BUGS.md: correct bug #8 root cause (CSP, not lazy-loading), add
  bugs #9 (grid spacing) and #10 (Windows taskbar badge)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/features/settings/account/ProfileDecoration.tsx

@@ -250,9 +250,10 @@ export function ProfileDecoration() {
                 style={{
                   display: 'flex',
                   flexWrap: 'wrap',
-                  gap: 20,
-                  paddingBottom: 4,
+                  gap: 36,
+                  paddingBottom: INSET,
                   paddingLeft: INSET,
+                  paddingRight: INSET,
                   paddingTop: INSET,
                 }}
               >