feat: refactor Docker setup, enhance README, and add legal pages with environment variable support

src/lib/env.ts

@@ -0,0 +1,21 @@
+const FALLBACK_SITE_URL = 'https://clock.arthurp.fr';
+const FALLBACK_CONTACT_URL = 'https://contact.arthurp.fr';
+const FALLBACK_CONTACT_EMAIL = 'contact@arthurp.fr';
+
+function normalizeUrl(value: string | undefined, fallback: string): string {
+  if (!value) {
+    return fallback;
+  }
+
+  try {
+    const parsed = new URL(value);
+    return parsed.origin;
+  } catch {
+    return fallback;
+  }
+}
+
+export const SITE_URL = normalizeUrl(process.env.SITE_URL, FALLBACK_SITE_URL);
+export const CONTACT_URL = normalizeUrl(process.env.CONTACT_URL, FALLBACK_CONTACT_URL);
+export const CONTACT_EMAIL = process.env.CONTACT_EMAIL?.trim() || FALLBACK_CONTACT_EMAIL;
+export const CONTACT_MAILTO = `mailto:${CONTACT_EMAIL}`;