Rewrite auth pages and emails with warm, friendly copy

[hendriebeats]

Summary

Many users may be new to Bible study and feel intimidated by the tool. This rewrites all user-facing text across sign-in, sign-up, password reset, error pages, and emails to feel welcoming, easygoing, and encouraging.

Bug fixes

• Remove insulting placeholder text on password reset page ("You Fool! How could you forget...") (lol Jon)
• Fix wrong "Sign Up" heading on the set-new-password page (now "Set New Password")
• Fix typos in token expiry error ("to long", "mintues")
• Replace placeholder welcome email body with real content
• Fix notAuthorized page incorrectly showing a 404 — now prompts to sign in
• Fix support@example.com → support@p215.church on notAuthorized page

Tone updates

• Login page: "Welcome Back" / "Sign in to continue your study."
• Signup page: "We're glad you're here! Create your account to get started."
• Password reset: "No worries — it happens! Enter your email and we'll help you get back in."
• Set new password: "Almost there! Just pick a new password."
• All error messages: Rewritten to be friendlier ("Hmm, that email or password doesn't look right. Give it another try!")
• Sidebar text (all auth pages): "Explore the Bible Together" / "No expertise required — just jump in and start studying with others."
• Home page hero: "Whether you're brand new to the Bible or have been studying for years, you belong here."
• Home CTA button: "GET STARTED" instead of "BEGIN YOUR JOURNEY"
• 404 page: "We couldn't find that page."
• Welcome email: Warm greeting replacing blank placeholder
• Password reset email: Softer "no worries" tone for the ignore-this line

Files changed

• backend/templates/login.html, login/form.html
• backend/templates/signup.html, signup/form.html
• backend/templates/passwordReset.html, passwordReset/form.html
• backend/templates/passwordResetToken.html
• backend/templates/notAuthorized.html, notFound.html
• backend/templates/home.html
• backend/lib/Emails/Welcome.hs, Emails/PasswordReset.hs
• backend/lib/Api/Htmx/PasswordReset.hs
• .gitignore