fix(marketing): A-2.8a — extract pricing partial + sync bento + OQLF + test calibration

- Extract 3 pricing tiers to templates/marketing/_partials/_pricing_tiers.html
  Single source of truth — landing.html and tarifs.html now {% include %} it.
  Prevents price drift (LPC art. 219 risk).
- Sync bento card #2 description across landing + fonctionnalites
  (was diverged: 'embeddings' vs 'embeddings vocaux'). Add maintenance
  reminder comments in both files.
- Fix OQLF NBSP on '~2 semaines' matrix cells in /tarifs deep-dive table.
- Fix mixed UTF-8/entity 'québécois' -> 'québécois' in tech
  specs (consistent with rest of file).
- Calibrate H2 size on /tarifs FAQ to match landing (clamp 2.75rem cap).
- Repair 2 pre-existing test bugs from earlier A-2.x commits:
  * 'violent la Loi 25' -> accept both NBSP and plain forms (commit 7c6c6fd
    added the NBSP after the test was written)
  * 'résilie' -> 'résilie' (Jinja outputs raw UTF-8, not entities)
- Update src/marketing/routes.py module docstring to reflect 2/4 done.

static/css/marketing.css

@@ -2303,9 +2303,6 @@
   .text-\[clamp\(2\.25rem\,4vw\,3\.5rem\)\] {
     font-size: clamp(2.25rem, 4vw, 3.5rem);
   }
-  .text-\[clamp\(2rem\,3vw\,2\.5rem\)\] {
-    font-size: clamp(2rem, 3vw, 2.5rem);
-  }
   .text-\[clamp\(2rem\,3vw\,2\.75rem\)\] {
     font-size: clamp(2rem, 3vw, 2.75rem);
   }