feat: add Open Graph image generation and SEO metadata

- Introduced `PageSeo` component for managing page metadata for social sharing.
- Created Open Graph image templates using SVG and static fonts for better visual representation.
- Implemented service alert management with functions to check active alerts and format route numbers.
- Added utility functions for generating and watching alert validity.
- Developed a script to generate Open Graph images dynamically based on page content.
- Included tests for service alert functionalities to ensure correctness and reliability.

assets/images/og-background.svg

@@ -0,0 +1,15 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="1136" height="566" viewBox="0 0 1136 566">
+  <defs>
+    <radialGradient id="blue" cx="1" cy="0" r="1">
+      <stop stop-color="#cfddf8" />
+      <stop offset="1" stop-color="#cfddf8" stop-opacity="0" />
+    </radialGradient>
+    <radialGradient id="purple" cx="0" cy="1" r="0.9">
+      <stop stop-color="#eadcee" />
+      <stop offset="1" stop-color="#eadcee" stop-opacity="0" />
+    </radialGradient>
+  </defs>
+  <path fill="#f7f9fd" d="M0 0h1136v566H0z" />
+  <path fill="url(#blue)" d="M0 0h1136v566H0z" />
+  <path fill="url(#purple)" d="M0 0h1136v566H0z" />
+</svg>