refactor(ui): sharpen buttons + inputs to rounded (4px) for modern minimal SaaS look

V2 sharper radii system aligned with Stripe Dashboard / Linear / Vercel
aesthetic — the v1 rounded-lg (8px) on buttons still felt too soft.

New scale:
- Buttons (CTA, submit, ghost, secondary): rounded-lg → rounded (4px)
- Form inputs (text/email/password/select/textarea): rounded-md → rounded (4px)
- Checkboxes: rounded-sm (2px) added explicitly to consent + remember-me
- Cards (pricing, bento, content panels): rounded-xl → rounded-lg (8px)
- Small icon tiles (w-10 h-10 / w-12 h-12 grad-bg squares): rounded-md → rounded
- Pills, badges, avatars, status orbs: rounded-full (KEPT)
- Inline code in legal CSS: rounded (4px) (KEPT)
- Legal blockquote/pre/draft-callout border-radius: 8px → 4px

Files modified (24):
- templates/macros/{button,bento,pricing_card}.html
- templates/marketing/{landing,tarifs,fonctionnalites,conformite,contact}.html
- templates/auth/{check_email,forgot_password,magic_link_request,
  oauth_finish_signup,passkey_setup,reset_password,totp_setup,totp_verify,
  verify_success}.html
- templates/billing/{success,cancel}.html
- templates/legal/{_layout,index}.html
- templates/{register,login}.html
- tests/test_marketing_landing_template.py (assertions updated to match v2)

Verification:
- 18/18 legal page tests pass (tests/_run_legal_pages_windows.py)
- 58/58 marketing landing tests pass

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

templates/auth/verify_success.html

@@ -5,7 +5,7 @@
 
 {% block content %}
 <section class="min-h-[calc(100vh-62px)] bg-brand-bg py-16 px-4" aria-labelledby="verify-success-title">
-  <div class="max-w-md mx-auto bg-white p-8 rounded-xl border border-brand-border shadow-cta text-center">
+  <div class="max-w-md mx-auto bg-white p-8 rounded-lg border border-brand-border shadow-cta text-center">
     <div class="mx-auto mb-6 w-16 h-16 rounded-full bg-green-100 text-green-700 flex items-center justify-center text-3xl font-black" aria-hidden="true">&check;</div>
 
     <h1 id="verify-success-title" class="text-2xl font-black text-brand-navy mb-2">Votre courriel a été vérifié</h1>
@@ -14,7 +14,7 @@
     </p>
 
     <a href="{{ url_for('auth.login') }}"
-       class="inline-block w-full grad-bg text-white font-semibold py-3 rounded-lg shadow-cta hover:shadow-cta-hover transition focus-visible:outline-2 focus-visible:outline-brand-b1 focus-visible:outline-offset-2">
+       class="inline-block w-full grad-bg text-white font-semibold py-3 rounded shadow-cta hover:shadow-cta-hover transition focus-visible:outline-2 focus-visible:outline-brand-b1 focus-visible:outline-offset-2">
       Se connecter
     </a>