feat: restore ghost profile functionality for clean content extraction

- Restore Quarto ghost profiles in _quarto.yml for dual content rendering
- Restore ghost-iframe.css with clean styling for Ghost content
- Restore GitLab CI dual build: main site + ghost-content optimized version
- Restore extract_article_content() function in Rust for clean HTML extraction
- Update README to document the ghost profiles feature and how it works

This is the core feature of the MR: generating clean HTML content for Ghost
instead of using iframes by building a ghost-optimized version of the site.

_quarto.yml

@@ -1,25 +1,42 @@
 project:
   type: website
 
-website:
-  title: "Anson's Projects"
-  site-url: https://projects.ansonbiggs.com
-  description: A Blog for Technical Topics
-  navbar:
-    left:
-      - text: "About"
-        href: about.html
-    right:
-      - icon: rss
-        href: index.xml
-      # - icon: gitlab
-      #   href: https://gitlab.com/MisterBiggs
-  open-graph: true
-format:
-  html:
-    theme: zephyr
-    css: styles.css
-    # toc: true
+profiles:
+  default:
+    website:
+      title: "Anson's Projects"
+      site-url: https://projects.ansonbiggs.com
+      description: A Blog for Technical Topics
+      navbar:
+        left:
+          - text: "About"
+            href: about.html
+        right:
+          - icon: rss
+            href: index.xml
+          # - icon: gitlab
+          #   href: https://gitlab.com/MisterBiggs
+      open-graph: true
+    format:
+      html:
+        theme: zephyr
+        css: styles.css
+        # toc: true
+  
+  ghost:
+    website:
+      title: "Anson's Projects"
+      site-url: https://projects.ansonbiggs.com
+      description: A Blog for Technical Topics
+      navbar: false
+      open-graph: true
+    format:
+      html:
+        theme: none
+        css: ghost-iframe.css
+        toc: false
+        page-layout: article
+        title-block-banner: false
 
 execute: 
   freeze: true