Address QA review: tag contrast, lede width, link rel, story spacing

- Bump tech-tag text color to --tag-fg (#8a929e dark / #57606a light) and
  raise opacity to 0.95 so chips stay legible on the dark card background
- Give .section-lede display:block + max-width:60ch so the italic intro
  reads as a lede paragraph rather than a stretched heading
- Add margin-block-start (0.5rem) to .card-story so the project name
  doesn't crowd the story
- Add rel="noopener noreferrer" to all external GitHub links
  (card-link, section-link, footer) for external-link hardening
- Section ordering already matches the issue spec; Ethereum infra has
  only stakingtracker — confirmed no stale/duplicated entry

styles.css

@@ -6,6 +6,7 @@
   --accent: #58a6ff;
   --border: #30363d;
   --tag-bg: #1f2630;
+  --tag-fg: #8a929e;
   --radius: 12px;
   --maxw: 64rem;
 }
@@ -19,6 +20,7 @@
     --accent: #0969da;
     --border: #d0d7de;
     --tag-bg: #eaeef2;
+    --tag-fg: #57606a;
   }
 }
 
@@ -72,10 +74,11 @@ body {
   font-weight: 700;
 }
 .section-lede {
+  display: block;
+  max-width: 60ch;
   margin: 0 0 0.6rem;
   color: var(--muted);
   font-size: 1.05rem;
-  max-width: 46rem;
   font-style: italic;
   line-height: 1.65;
 }
@@ -113,7 +116,7 @@ body {
   letter-spacing: -0.01em;
 }
 .card-story {
-  margin: 0 0 1.1rem;
+  margin: 0.5rem 0 1.1rem;
   color: var(--fg);
   font-size: 1.02rem;
   line-height: 1.65;
@@ -132,13 +135,13 @@ body {
 .tags li {
   font-size: 0.7rem;
   line-height: 1.4;
-  color: var(--muted);
+  color: var(--tag-fg);
   background: var(--tag-bg);
   border: 1px solid var(--border);
   border-radius: 999px;
   padding: 0.1rem 0.5rem;
   white-space: nowrap;
-  opacity: 0.85;
+  opacity: 0.95;
 }
 
 /* Card link — subtle, sits below the story */