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>

tests/test_marketing_landing_template.py

@@ -268,7 +268,7 @@ def test_bento_uses_flexihub_styling():
     assert 'gap-[1.5px]' in body, "Missing FlexiHub ultrafin separator gap"
     assert 'bg-brand-navy2' in body, "Missing dark card background"
     assert 'text-white/[0.04]' in body, "Missing FlexiHub watermark opacity"
-    assert 'grad-bg rounded-[0.5rem]' in body, "Missing gradient icon corner"
+    assert 'grad-bg rounded-md' in body, "Missing gradient icon corner"
 
 
 def test_bento_responsive_grid():
@@ -333,8 +333,8 @@ def test_pricing_recommended_tier_is_dictia_16():
     client = app.test_client()
     body = client.get('/').data.decode('utf-8')
     assert 'RECOMMAND' in body, "Missing RECOMMANDÉ badge"
-    # The recommended tier wraps in grad-bg p-[1.5px] rounded-[20px] FlexiHub style
-    assert 'grad-bg p-[1.5px] rounded-[20px]' in body, "Missing FlexiHub gradient frame on recommended tier"
+    # The recommended tier wraps in grad-bg p-[1.5px] rounded-xl FlexiHub style (12px modern)
+    assert 'grad-bg p-[1.5px] rounded-xl' in body, "Missing FlexiHub gradient frame on recommended tier"
 
 
 def test_pricing_cta_uses_reserver_pre_launch_wording():