feat(unionflow): ajout Spec-Kit, constitution, mission mutuelles

- Config Spec-Kit pour Spec-Driven Development
- CONSTITUTION.md + .specify/memory/constitution.md
- Commandes Cursor /speckit.*, règles projet
- Mission: associations + mutuelles d'épargne et de financement
- .gitignore: versionner config spec-kit unionflow

Made-with: Cursor

unionflow/unionflow-mobile-apps/android/.gitignore

@@ -0,0 +1,13 @@
+gradle-wrapper.jar
+/.gradle
+/captures/
+/gradlew
+/gradlew.bat
+/local.properties
+GeneratedPluginRegistrant.java
+
+# Remember to never publicly share your keystore.
+# See https://flutter.dev/to/reference-keystore
+key.properties
+**/*.keystore
+**/*.jks