refactor(ui): V3 fully square buttons + inputs (rounded-none, brutalist/Swiss aesthetic)

V3 finalizes the radii pass to a fully brutalist/Swiss visual language:

- Buttons (CTAs, submit, secondary, ghost, OAuth provider tiles): rounded-none (0px)
- Form inputs (text/email/password/select/textarea/code-entry): rounded-none (0px)
- Checkboxes: rounded-none (0px) — was rounded-sm
- Small icon tiles (w-10 h-10 / w-12 h-12 grad-bg squares): rounded-none (0px)
- Inline code blocks (totp recovery <pre>, secret <code>): rounded-none (0px)
- Cards (pricing, bento, content panels, modals, prev/next nav): rounded (4px) — was rounded-lg
- Alert / flash boxes: rounded (4px) — was rounded-lg
- Pills, badges, status chips, ordres pros avatars, decorative cosmic orbs: rounded-full preserved
- Legal _layout.html inline <style> blockquote/pre/code/draft-callout: border-radius 0 — was 4px

Updated tests/test_marketing_landing_template.py assertions:
- bento icon assertion: "grad-bg rounded " -> "grad-bg rounded-none "
- pricing recommended frame: "rounded-lg" -> "rounded" (with strict trailing-char match to avoid rounded-none false positive)

Verification: 18/18 legal tests pass, 58/58 marketing landing tests pass, 5/5 root redirect tests pass. Two pre-existing failures in test_marketing_secondary_pages (SOC 2 hedge text + gitea.innova-ai.ca URL) are unrelated to this radii pass.

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 ' in body, "Missing gradient icon corner"
+    assert 'grad-bg rounded-none ' in body, "Missing gradient icon corner (V3 brutalist square)"
 
 
 def test_bento_responsive_grid():
@@ -333,8 +333,9 @@ 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-lg FlexiHub style (8px sharper SaaS)
-    assert 'grad-bg p-[1.5px] rounded-lg' in body, "Missing FlexiHub gradient frame on recommended tier"
+    # The recommended tier wraps in grad-bg p-[1.5px] rounded FlexiHub style (V3 brutalist 4px card frame)
+    assert 'grad-bg p-[1.5px] rounded"' in body or 'grad-bg p-[1.5px] rounded ' in body, \
+        "Missing FlexiHub gradient frame on recommended tier (rounded 4px)"
 
 
 def test_pricing_cta_uses_reserver_pre_launch_wording():