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.

src/marketing/routes.py

@@ -2,7 +2,7 @@
 
 Phase 2 (A-2.1+): renders templates/marketing/landing.html.
 Tasks A-2.2 through A-2.7 will progressively enrich the landing template.
-Tasks A-2.8 will add /tarifs, /fonctionnalites, /conformite, /contact routes.
+Task A-2.8a added /tarifs and /fonctionnalites; A-2.8b will add /conformite and /contact.
 """
 from flask import render_template