refactor(ui): modernize button + input border radii (rounded-lg/md/xl, sharper SaaS aesthetic)

Aligns DictIA marketing/auth/legal/billing templates with modern SaaS visual
conventions (Linear, Vercel, Stripe Dashboard, Notion). Old radii (12-18px)
felt dated; new system uses 6-12px for tighter, more contemporary corners.

Border radius system:
- Buttons (CTA, submit, secondary): rounded-[0.75rem] (12px) -> rounded-lg (8px)
- Form inputs (text/email/password/select/textarea/checkbox): rounded-[0.5rem] -> rounded-md (6px)
- Cards (pricing, bento, modals, content panels): rounded-[18px]/[14px]/[12px] -> rounded-xl (12px)
- Pricing card outer gradient frame: rounded-[20px] -> rounded-xl (matches inner)
- Pills / badges / status chips: KEEP rounded-full
- Avatars / circular icon containers: KEEP rounded-full
- Code blocks: KEEP rounded (4px)

Decision tree applied for ambiguous cases:
- Button-like clickable CTA -> rounded-lg
- Form input -> rounded-md
- Card / panel / modal -> rounded-xl
- Badge / pill / chip / avatar -> rounded-full (preserved)

In-scope templates modified (23):
- macros/button.html (central macro, cascades to all callers)
- macros/pricing_card.html, macros/bento.html
- marketing/landing.html, tarifs.html, fonctionnalites.html, conformite.html, contact.html
- auth/check_email.html, forgot_password.html, magic_link_request.html, oauth_finish_signup.html,
  passkey_setup.html, reset_password.html, totp_setup.html, totp_verify.html, verify_success.html
- billing/cancel.html, billing/success.html
- legal/_layout.html, legal/index.html
- register.html, login.html

Out of scope (untouched): index.html, account.html, admin.html, share.html, inquire.html,
group-admin.html, components/**, includes/**, modals/** (all legacy Speakr Vue surfaces).

Tests: test_marketing_landing_template.py — 2 assertions updated to match new bento icon
(rounded-md) and pricing card frame (rounded-xl). All 18 legal tests + 58 marketing landing
tests + 9 signup_loi25 tests still pass. Decorative rounded-full preserved on hero cosmic
orbs and ordres-pros avatar circles.

Diff: 94 insertions / 94 deletions (1:1 mechanical replacement, no class drift).

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

templates/marketing/conformite.html

@@ -52,8 +52,8 @@
           'desc': 'Fork du projet open source Speakr — architecture entièrement auditable sur <a href="https://gitea.dictia.ca/Innova-AI/dictia-public" target="_blank" rel="noopener" class="underline hover:text-brand-navy">Gitea public</a>. Aucune boîte noire. Vos auditeurs peuvent examiner chaque ligne.'
         }
       ] %}
-      <article class="bg-brand-bg p-6 rounded-[14px] border border-brand-border">
-        <div class="w-10 h-10 grad-bg rounded-[0.5rem] mb-4 flex items-center justify-center text-lg shadow-cta" aria-hidden="true">{{ card.icon }}</div>
+      <article class="bg-brand-bg p-6 rounded-xl border border-brand-border">
+        <div class="w-10 h-10 grad-bg rounded-md mb-4 flex items-center justify-center text-lg shadow-cta" aria-hidden="true">{{ card.icon }}</div>
         <h3 class="text-lg font-bold mb-2 text-brand-navy">{{ card.title | safe }}</h3>
         <p class="text-sm text-brand-navy/80 leading-relaxed">{{ card.desc | safe }}</p>
       </article>
@@ -93,7 +93,7 @@
           'desc': 'Avant tout enregistrement, DictIA exige une confirmation que les participants ont consenti à l\'enregistrement et à la transcription IA. Le consentement est tracé dans le journal d\'audit. Vous pouvez configurer une demande de consentement automatique en début de session.'
         }
       ] %}
-      <article class="bg-white p-6 rounded-[14px] border border-brand-border">
+      <article class="bg-white p-6 rounded-xl border border-brand-border">
         <div class="flex flex-col md:flex-row md:items-start gap-4">
           <div class="flex-shrink-0">
             <span class="inline-block bg-brand-navy text-white text-xs font-black px-3 py-1.5 rounded-md">{{ art.num | safe }}</span>