style(brand): unify orange to #FA7850 + yellow token; fix tablet header gap

- Brand orange is now the official #FA7850 everywhere: folded the stray
  oranges (#F2762E, #E8833A, #ff6b2c) into it and kept a single darker shade
  (#E85D2A) for gradient depth + button hover. Added the official brand
  --yellow (#FFE16E) token.
- Tablet header gap (769-1024px): the fixed header shrinks 80->60px there but
  first-section paddings kept their 80px clearance; pull the first section up
  by the 20px delta in that range only (phones untouched). Verified on
  interior pages and the full-bleed homepage hero — gap now matches desktop,
  no overlap.
- Re-stamped cache-bust (v=f95de694).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

css/pages/_blog.css

@@ -6,7 +6,7 @@
 /* Topic colours */
 .blog-page {
     --t-student-life: #2D738C;
-    --t-study-tips:   #E8833A;
+    --t-study-tips:   #FA7850;
     --t-slovenia:     #3B82C4;
     --t-community:    #7C5CBF;
     --t-guides:       #2E9E6B;
@@ -20,7 +20,7 @@
 }
 .blog-eyebrow {
     display: inline-block;
-    color: #E8833A;
+    color: #FA7850;
     font-weight: 700;
     font-size: 14px;
     letter-spacing: 0.06em;