Fix remaining lint: blank line before fenced blocks + trailing spaces

Author: HKTITAN

skills/design-engineering/references/components/hover-states-subtle.md

@@ -76,6 +76,7 @@ Disabled elements should be visually distinct but not dead:
 ```
 
 But for inputs:
+
 ```css
 .input:disabled {
   background-color: var(--bg-disabled); /* not just opacity */

skills/design-engineering/references/motion/animation-decision-framework.md

@@ -17,7 +17,7 @@ The most-skipped step in design engineering is asking "should this animate at al
    - **Feedback** — confirm the action happened.
    - **Hierarchy** — direct attention to one thing over another.
    - **Spatial** — clarify where something came from or went to.
-   
+
    Invalid purposes:
    - **Decoration** — animation as garnish.
    - **Filling time** — animation to mask slow code (fix the code).

skills/design-engineering/references/typography/line-length-tracking.md

@@ -14,6 +14,7 @@ For prose: 60–70 characters per line is the sweet spot.
 For UI labels and form fields: shorter is fine; you control them.
 
 CSS:
+
 ```css
 .prose {
   max-width: 65ch;