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-agent-builder/references/template-substitution-rules.md

@@ -0,0 +1,47 @@
+# Template Substitution Rules
+
+The SKILL-template provides a minimal skeleton: frontmatter, overview, agent identity sections, sidecar, 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., `cis-`) or empty for standalone
+- `{agent-name}` → Agent functional name (kebab-case)
+- `{skill-description}` → Two parts: [4-6 word summary]. [trigger phrases]
+- `{displayName}` → Friendly display name
+- `{skillName}` → Full skill name with module prefix
+
+## Module Conditionals
+
+### For Module-Based Agents
+
+- `{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., `cis`)
+- `{module-setup-skill}` → Name of the module's setup skill (e.g., `bmad-cis-setup`)
+
+### For Standalone Agents
+
+- `{if-module}` ... `{/if-module}` → Remove the entire block including markers
+- `{if-standalone}` ... `{/if-standalone}` → Keep the content inside
+
+## Sidecar Conditionals
+
+- `{if-sidecar}` ... `{/if-sidecar}` → Keep if agent has persistent memory, otherwise remove
+- `{if-no-sidecar}` ... `{/if-no-sidecar}` → Inverse of above
+
+## Headless Conditional
+
+- `{if-headless}` ... `{/if-headless}` → Keep if agent supports headless mode, otherwise remove
+
+## Beyond the Template
+
+The builder determines the rest of the agent structure — capabilities, activation flow, sidecar initialization, capability routing, external skills, scripts — based on the agent's requirements. The template intentionally does not prescribe these.
+
+## Path References
+
+All generated agents use `./` prefix for skill-internal paths:
+
+- `./references/init.md` — First-run onboarding (if sidecar)
+- `./references/{capability}.md` — Individual capability prompts
+- `./references/memory-system.md` — Memory discipline (if sidecar)
+- `./scripts/` — Python/shell scripts for deterministic operations