feat: scaffold Astro project with layout, nav, hero and concept sections

- Add global ocean-themed styles (Inter + Sora, glassmorphism utilities).
- Wire up base layout, sticky nav and footer respecting base path.
- Build hero with stylised rock SVG + sonar ambient rings and concept pipeline schematic.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tsconfig.json

@@ -0,0 +1,9 @@
+{
+  "extends": "astro/tsconfigs/strict",
+  "compilerOptions": {
+    "baseUrl": ".",
+    "paths": {
+      "~/*": ["src/*"]
+    }
+  }
+}