feat: Calculer automatiquement les moyennes après chaque saisie de notes

Les enseignants ont besoin de moyennes à jour immédiatement après la
publication ou modification des notes, sans attendre un batch nocturne.

Le système recalcule via Domain Events synchrones : statistiques
d'évaluation (min/max/moyenne/médiane), moyennes matières pondérées
(normalisation /20), et moyenne générale par élève. Les résultats sont
stockés dans des tables dénormalisées avec cache Redis (TTL 5 min).

Trois endpoints API exposent les données avec contrôle d'accès par rôle.
Une commande console permet le backfill des données historiques au
déploiement.

.agents/skills/bmad-workflow-builder/references/template-substitution-rules.md

@@ -0,0 +1,35 @@
+# Template Substitution Rules
+
+The SKILL-template provides a minimal skeleton: frontmatter, overview, and activation with config loading. Everything beyond that is crafted by the builder based on what was learned during discovery and requirements phases.
+
+## Frontmatter
+
+- `{module-code-or-empty}` → Module code prefix with hyphen (e.g., `bmb-`) or empty for standalone
+- `{skill-name}` → Skill functional name (kebab-case)
+- `{skill-description}` → Two parts: [5-8 word summary]. [trigger phrases]
+
+## Module Conditionals
+
+### For Module-Based Skills
+
+- `{if-module}` ... `{/if-module}` → Keep the content inside
+- `{if-standalone}` ... `{/if-standalone}` → Remove the entire block including markers
+- `{module-code}` → Module code without trailing hyphen (e.g., `bmb`)
+- `{module-setup-skill}` → Name of the module's setup skill (e.g., `bmad-builder-setup`)
+
+### For Standalone Skills
+
+- `{if-module}` ... `{/if-module}` → Remove the entire block including markers
+- `{if-standalone}` ... `{/if-standalone}` → Keep the content inside
+
+## Beyond the Template
+
+The builder determines the rest of the skill structure — body sections, phases, stages, scripts, external skills, headless mode, role guidance — based on the skill type classification and requirements gathered during the build process. The template intentionally does not prescribe these; the builder has the context to craft them.
+
+## Path References
+
+All generated skills use `./` prefix for skill-internal paths:
+
+- `./references/{reference}.md` — Reference documents loaded on demand
+- `./references/{stage}.md` — Stage prompts (complex workflows)
+- `./scripts/` — Python/shell scripts for deterministic operations