Add SMS consent logging for Twilio compliance

Log phone, IP, and user agent to sms_consents table before sending
verification SMS. Add disclosure text to login form.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

db/queries.sql.go

@@ -181,6 +181,21 @@ func (q *Queries) CreateSlot(ctx context.Context, arg CreateSlotParams) (Slot, e
 	return i, err
 }
 
+const createSmsConsent = `-- name: CreateSmsConsent :exec
+INSERT INTO sms_consents (phone, ip_address, user_agent) VALUES (?, ?, ?)
+`
+
+type CreateSmsConsentParams struct {
+	Phone     string
+	IpAddress string
+	UserAgent string
+}
+
+func (q *Queries) CreateSmsConsent(ctx context.Context, arg CreateSmsConsentParams) error {
+	_, err := q.db.ExecContext(ctx, createSmsConsent, arg.Phone, arg.IpAddress, arg.UserAgent)
+	return err
+}
+
 const createUserByEmail = `-- name: CreateUserByEmail :one
 INSERT INTO users (email, name) VALUES (?, '') RETURNING id, phone, email, name, created_at
 `