fix: address P1 and P2 issues from code review

- Remove set:html XSS risk in Footer (#208)
- Fix hardcoded JSON-LD URLs to use Astro.site (#209)
- Fix dark mode link contrast for WCAG AAA (#210)
- Remove unused search box CSS (#211)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: braboj

astro-site/src/components/Footer.astro

@@ -3,5 +3,5 @@ import site from "../data/site.json";
 ---
 
 <footer class="site-footer">
-  <Fragment set:html={site.copyright} />
+  {site.copyright}
 </footer>

astro-site/src/pages/[...slug].astro

@@ -37,7 +37,7 @@ const jsonLd = {
   "isPartOf": {
     "@type": "Course",
     "name": "Git Tutorial — Code with Branko",
-    "url": "https://braboj.github.io/tutorial-git/"
+    "url": new URL(import.meta.env.BASE_URL, import.meta.env.SITE).toString()
   }
 };
 ---

astro-site/src/pages/index.astro

@@ -16,7 +16,7 @@ const jsonLd = {
   "@type": "Course",
   "name": "Git Tutorial — Code with Branko",
   "description": "A hands-on Git tutorial from first commit to confident daily use — concepts, exercises, and real-world examples.",
-  "url": "https://braboj.github.io/tutorial-git/",
+  "url": new URL(import.meta.env.BASE_URL, import.meta.env.SITE).toString(),
   "provider": {
     "@type": "Person",
     "name": "Branimir Georgiev",

astro-site/src/styles/global.css

@@ -55,8 +55,8 @@
   --color-fg-muted: #aaaaaa;
   --color-fg-faint: #888888;
   --color-border: #ffffff1f;
-  --color-link: #4dd0e1;
-  --color-focus: #4dd0e1;
+  --color-link: #00bcd4;
+  --color-focus: #00bcd4;
   --color-code-bg: #2a2a2a;
   --color-code-fg: #e0e0e0;
 }
@@ -169,44 +169,6 @@ a:hover {
   gap: var(--space-sm);
 }
 
-/* Search box */
-.search-box {
-  position: relative;
-  display: flex;
-  align-items: center;
-}
-
-.search-icon {
-  position: absolute;
-  left: 0.5rem;
-  color: #fff;
-  opacity: 0.7;
-  pointer-events: none;
-}
-
-.search-box input {
-  background: rgba(255, 255, 255, 0.15);
-  border: none;
-  border-radius: 3px;
-  color: #fff;
-  font-family: var(--font-text);
-  font-size: var(--font-size-sm);
-  padding: 0.35rem 0.5rem 0.35rem 2rem;
-  width: 10rem;
-  transition: background 0.2s, width 0.2s;
-}
-
-.search-box input::placeholder {
-  color: rgba(255, 255, 255, 0.7);
-}
-
-.search-box input:focus-visible {
-  background: rgba(255, 255, 255, 0.25);
-  width: 14rem;
-  outline: 2px solid #fff;
-  outline-offset: 1px;
-}
-
 /* Theme toggle */
 .theme-toggle {
   background: none;