Add contact antispam and fix gallery video playback.

English-only messages, rate limiting, min fill time, and normalized email
validation; improve modal video serving with posters, correct MIME types, and
no gzip on gallery media.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/internal/contact/validate.go

@@ -1,16 +1,19 @@
 package contact
 
 import (
+	"errors"
 	"net/mail"
 	"strings"
 	"unicode/utf8"
+
+	"technical.kiwi/website/internal/contactcheck"
 )
 
 const (
 	maxNameLen    = 120
 	maxEmailLen   = 254
 	maxMessageLen = 8000
-	minMessageLen = 10
+	minMessageLen = 20
 )
 
 // Submission is validated contact form input.
@@ -45,18 +48,40 @@ func Parse(name, email, message string) (Submission, Errors) {
 		errs["email"] = "Email is required."
 	} else if utf8.RuneCountInString(email) > maxEmailLen {
 		errs["email"] = "Email is too long."
-	} else if _, err := mail.ParseAddress(email); err != nil {
-		errs["email"] = "Enter a valid email address."
+	} else {
+		addr, err := mail.ParseAddress(email)
+		if err != nil {
+			errs["email"] = "Enter a valid email address."
+		} else {
+			email = addr.Address
+		}
 	}
 
 	if message == "" {
 		errs["message"] = "Message is required."
 	} else if utf8.RuneCountInString(message) < minMessageLen {
-		errs["message"] = "Message must be at least 10 characters."
+		errs["message"] = "Message must be at least 20 characters."
 	} else if utf8.RuneCountInString(message) > maxMessageLen {
 		errs["message"] = "Message is too long."
 	}
 
+	if !errs.Any() {
+		if err := contactcheck.ValidateEnglish(name, message); err != nil {
+			switch {
+			case errors.Is(err, contactcheck.ErrTooShort):
+				errs["message"] = "Message must be at least 20 characters."
+			case errors.Is(err, contactcheck.ErrTooLong):
+				errs["message"] = "Message is too long."
+			case errors.Is(err, contactcheck.ErrName):
+				errs["name"] = "Name is too long."
+			case errors.Is(err, contactcheck.ErrNotEnglish):
+				errs["message"] = "This site only accepts messages written in English. If your message is in English, try adding a few more clear sentences so we can detect the language reliably."
+			default:
+				errs["message"] = "Could not accept this message."
+			}
+		}
+	}
+
 	if errs.Any() {
 		return Submission{}, errs
 	}