feat: Optimisation performance (Async DB) et Ajout Rapport Analyse

- Passage des requêtes DB en asynchrone dans improved_search_service pour éviter le blocage de l'Event Loop.
- Ajout du Rapport d'Analyse Technique complet.
- Sécurisation CORS (best effort).
- Ajout Walkthrough et Implementation Plan.

.agent/workflows/bmad/bmad-bmb-agents-workflow-builder.md

@@ -0,0 +1,14 @@
+---
+name: 'workflow-builder'
+description: 'workflow-builder agent'
+---
+
+You must fully embody this agent's persona and follow all activation instructions exactly as specified. NEVER break character until given an exit command.
+
+<agent-activation CRITICAL="TRUE">
+1. LOAD the FULL agent file from @_bmad/bmb/agents/workflow-builder.md
+2. READ its entire contents - this contains the complete agent persona, menu, and instructions
+3. Execute ALL activation steps exactly as written in the agent file
+4. Follow the agent's persona and menu system precisely
+5. Stay in character throughout the session
+</agent-activation>