fix: about page — Construit avec, Dernière livraison, Tests, Git labels

- h3 Construit avec -> data-i18n about.built_with
- Derniere livraison span -> data-i18n about.last_delivery
- Tests stat label -> data-i18n about.tests
- Git label -> data-i18n about.git
- Root cause: pattern mismatch (CONSTRUIT AVEC vs Construit avec)

frontend/locales/en.json

@@ -654,8 +654,8 @@
   "help.welcome_tag4": "📝 Reading & editing",
   "help.welcome_tag5": "🔍 TF-IDF search",
   "about.subtitle": "Your Obsidian notes, simply accessible.",
-  "about.built_with": "BUILT WITH",
-  "about.last_delivery": "Last delivery",
+  "about.built_with": "Built with",
+  "about.last_delivery": "Last delivery&nbsp;: <strong id=\"about-build-date\">June 2026</strong>",
   "about.fun_quote": "\"No LLM was harmed during this development.\"",
   "about.footer": "Made with ☕, 🍕 and a few accidental git push --force.",
   "header.menu_theme": "Theme",
@@ -1232,5 +1232,7 @@
   "about.joke_6": "Dark mode active since the project's birth.",
   "about.joke_7": "Works on my machine™",
   "about.joke_8": "Technically, everything is an edge case.",
-  "about.joke_9": "The CSS for this panel took longer than the backend."
+  "about.joke_9": "The CSS for this panel took longer than the backend.",
+  "about.tests": "Tests",
+  "about.git": "Git&nbsp;: <strong id=\"about-commit\">—</strong>"
 }

frontend/locales/fr.json

@@ -654,8 +654,8 @@
   "help.welcome_tag4": "📖 Lecture et édition",
   "help.welcome_tag5": "🔍 Recherche TF-IDF",
   "about.subtitle": "Vos notes Obsidian, simplement accessibles.",
-  "about.built_with": "CONSTRUIT AVEC",
-  "about.last_delivery": "Dernière livraison",
+  "about.built_with": "Construit avec",
+  "about.last_delivery": "Dernière livraison&nbsp;: <strong id=\"about-build-date\">Juin 2026</strong>",
   "about.fun_quote": "« Aucun LLM n'a été blessé durant ce développement. »",
   "about.footer": "Fait avec ☕, 🍕 et quelques git push --force accidentels.",
   "header.menu_theme": "Thème",
@@ -1232,5 +1232,7 @@
   "about.joke_6": "Dark mode activé depuis la naissance du projet.",
   "about.joke_7": "Ça marche sur ma machine™",
   "about.joke_8": "Techniquement, tout est un edge case.",
-  "about.joke_9": "Le CSS de ce panneau a pris plus de temps que le backend."
+  "about.joke_9": "Le CSS de ce panneau a pris plus de temps que le backend.",
+  "about.tests": "Tests",
+  "about.git": "Git&nbsp;: <strong id=\"about-commit\">—</strong>"
 }