Expand konesali page content and add illustrations across all pages

- Konesali: add descriptive paragraphs to all 6 sections (sähkö, jäähdytys,
  tietoliikenne, turvallisuus, tilat, ympäristö) with detailed explanations
- Konesali: add decorative SVG illustrations to all sections
- Yhteydet: add illustrations to yhteyspaketit and operaattorit sections
- Index: add illustrations to hinnat and miksi sections
- CSS: add .spec-intro style for descriptive text blocks

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

style.css

@@ -1210,6 +1210,22 @@ a:hover {
     font-size: 1rem;
 }
 
+.spec-intro {
+    color: var(--color-text-body);
+    line-height: 1.75;
+    max-width: 800px;
+    margin-bottom: 30px;
+    font-size: 0.98rem;
+}
+
+.section-dark .spec-intro {
+    color: rgba(255, 255, 255, 0.75);
+}
+
+.section-green .spec-intro {
+    color: var(--color-text-body);
+}
+
 .spec-table {
     background: var(--color-white);
     border: 1px solid var(--color-border);