Add contact actions and migrate contact form to Astro actions

Implement send_otp and send_msg handlers with server-side validation,
captcha verification, OTP generation/verification, rate limiting,
session-backed multi-step flow, and SMS gateway integration.

Replace broken contact endpoint and types with Astro server actions;
delete endpoints/contact.ts, types/ContactForm.ts and
src/components/ContactForm.astro. Update pages/contact.astro to use
astro:actions and improve captcha handling (listen for solve and set
hidden input). Adjust OTP timing (step 60s → 300s, VALID_PAST_OTP_STEPS
5 → 1). Add validator, @types/validator, Prettier and
prettier-plugin-astro; include .prettierrc.mjs in tsconfig include.

Add Prettier config for Astro

tsconfig.json

@@ -1,6 +1,6 @@
 {
   "extends": "astro/tsconfigs/strict",
-  "include": [".astro/types.d.ts", "**/*"],
+  "include": [".astro/types.d.ts", "**/*", ".prettierrc.mjs"],
   "exclude": ["dist"],
   "compilerOptions": {
     "verbatimModuleSyntax": true,
@@ -9,7 +9,7 @@
       "@layouts/*": ["./src/layouts/*"],
       "@lib/*": ["./src/lib/*"],
       "@pages/*": ["./src/pages/*"],
-      "@types/*": ["./src/types/*"],
+      "@actions/*": ["./src/actions/*"],
     },
     "plugins": [
       {