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/marketing/fonctionnalites.html

@@ -25,7 +25,7 @@
     {# NOTE: bento card content is duplicated between landing.html and fonctionnalites.html.
        When editing, sync both files. Future refactor: extract to _partials/_bento_features.html. #}
     {% from 'macros/bento.html' import bento_card %}
-    <div class="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 gap-[1.5px] bg-brand-border rounded-xl overflow-hidden">
+    <div class="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 gap-[1.5px] bg-brand-border rounded-lg overflow-hidden">
       {{ bento_card('01', 'Transcription WhisperX', 'Large-v3 fine-tuné FR-CA. Précision 95&nbsp;%+ sur réunions, dictées, audiences (méthodologie disponible sur demande).', '🎙️') }}
       {{ bento_card('02', 'Diarisation 8 locuteurs', 'pyannote sépare automatiquement les intervenants. Identification par embeddings vocaux.', '👥') }}
       {{ bento_card('03', 'Résumés Mistral 7B', 'IA locale génère résumés, points d\'action et procès-verbaux. Aucune connexion cloud.', '📝') }}
@@ -55,7 +55,7 @@
         {'ext': 'JSON', 'use': 'Pipeline développeur'},
         {'ext': 'MD',   'use': 'Notion, Obsidian, GitHub'}
       ] %}
-      <div class="bg-white p-4 rounded-xl border border-brand-border text-center">
+      <div class="bg-white p-4 rounded-lg border border-brand-border text-center">
         <p class="text-base font-black text-brand-navy">{{ fmt.ext }}</p>
         <p class="text-xs text-brand-navy/70 mt-1">{{ fmt.use | safe }}</p>
       </div>
@@ -87,7 +87,7 @@
         {'name': 'Make (Integromat)', 'desc': 'Scénarios visuels'},
         {'name': 'n8n', 'desc': 'Open source self-host'}
       ] %}
-      <div class="bg-brand-bg p-5 rounded-xl border border-brand-border text-center">
+      <div class="bg-brand-bg p-5 rounded-lg border border-brand-border text-center">
         <p class="text-base font-bold text-brand-navy">{{ integ.name | safe }}</p>
         <p class="text-xs text-brand-navy/70 mt-1">{{ integ.desc | safe }}</p>
       </div>