feat(auth): B-2.3 emails FR + DictIA branding (SMTP Resend)

Rebrand src/services/email.py IN PLACE: French + DictIA + brand gradient
(#0062ff/#00bdd8/#00c896) — replaces legacy "Speakr" / #2563eb. Greetings now
use user.name with fallback to user.username. Subjects:
"Vérifiez votre courriel — DictIA" + "Réinitialiser votre mot de passe — DictIA".
SMTP_FROM_NAME defaults to DictIA. Footer points to info@dictia.ca with the
Loi 25 tagline.

Refonte 4 auth templates IN PLACE pour étendre marketing/base.html : check_email,
forgot_password, reset_password, verify_success. Tokens DictIA (brand-navy,
brand-bg, grad-bg, shadow-cta), French copy, WCAG patterns (label for,
focus-visible:outline-2, role=alert, aria-required, text-brand-navy/70 minimum,
NBSP français pour Loi 25 / 24 heures / 1 heure / 8 caractères).

Translate inline French flash messages in src/api/auth.py for /verify-email,
/resend-verification, /forgot-password, /reset-password. Anti-enumeration fix:
forgot_password no longer flashes the cooldown remaining (would leak account
existence) — silently skips resend, generic flash unchanged. Cooldown logic
in src/services/email.py UNCHANGED (60s — verified by test).

config/env.email.example: defaults to Resend SMTP at the top + adds Resend
to the provider examples list (preserves Gmail/SendGrid/Mailgun/SES/M365).

Tests: tests/test_email_service_dictia.py — 12 tests covering DictIA branding,
French copy, display-name fallback, anti-enumeration parity (forgot_password
returns identical message for known/unknown emails), 60s cooldown, SMTP-not-
configured returns False (no exception), check_email.html extends marketing/base
(no var(--text-primary) leaks). Includes Windows manual driver
(_run_email_service_dictia_windows.py) since pytest cannot collect on Windows
native (fcntl POSIX-only).

NO new dependency added (no resend SDK — SMTP via existing _send_email).
NO new route added or removed.
NO src/auth_extended/ created.
NO change to itsdangerous-based token logic.
templates/auth/**/*.html already in tailwind.config.js content array (B-2.2).

Verified locally on Windows manual driver: 12/12 PASS B-2.3, 9/9 PASS regression
on B-2.2 signup, 9/9 PASS regression on B-2.1 ConsentLog.

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

static/css/marketing.css

@@ -747,9 +747,6 @@
   .h-16 {
     height: calc(var(--spacing) * 16);
   }
-  .h-20 {
-    height: calc(var(--spacing) * 20);
-  }
   .h-24 {
     height: calc(var(--spacing) * 24);
   }
@@ -1668,9 +1665,6 @@
   .bg-\[var\(--bg-warn-light\)\] {
     background-color: var(--bg-warn-light);
   }
-  .bg-\[var\(--bg-warning-light\)\] {
-    background-color: var(--bg-warning-light);
-  }
   .bg-\[var\(--border-accent\)\] {
     background-color: var(--border-accent);
   }