feat: add site mail signature

src/mailer/mail-templates/adminStructureClaim.ejs

src/mailer/mail-templates/apticStructureDuplication.ejs

src/mailer/mail-templates/changeEmail.ejs

src/mailer/mail-templates/resetPassword.ejs

src/mailer/mail-templates/structureClaimValidation.ejs

src/mailer/mail-templates/structureJoinRequest.ejs

src/mailer/mail-templates/structureOutdatedInfo.ejs

src/mailer/mail-templates/tempUserRegistration.ejs

src/mailer/mail-templates/verify.ejs

src/mailer/mailer.service.ts