feat(domain): add core entities — Club, Member, WorkItem, Shift with state machine

- Create domain entities in WorkClub.Domain/Entities: Club, Member, WorkItem, Shift, ShiftSignup
- Implement enums: SportType, ClubRole, WorkItemStatus
- Add ITenantEntity interface for multi-tenancy support
- Implement state machine validation on WorkItem with C# 14 switch expressions
- Valid transitions: Open→Assigned→InProgress→Review→Done, Review→InProgress (rework)
- All invalid transitions throw InvalidOperationException
- TDD approach: Write tests first, 12/12 passing
- Use required properties with explicit Guid/Guid? for foreign keys
- DateTimeOffset for timestamps (timezone-aware, multi-tenant friendly)
- RowVersion byte[] for optimistic concurrency control
- No navigation properties yet (deferred to EF Core task)
- No domain events or validation attributes (YAGNI for MVP)

infra/k8s/base/configmap.yaml

@@ -0,0 +1,41 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: workclub-config
+  labels:
+    app: workclub
+data:
+  log-level: "Information"
+  cors-origins: "http://localhost:3000"
+  api-base-url: "http://workclub-api"
+  keycloak-url: "http://workclub-keycloak"
+  keycloak-realm: "workclub"
+  
+  # Database configuration
+  database-host: "workclub-postgres"
+  database-port: "5432"
+  database-name: "workclub"
+
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: postgres-init
+  labels:
+    app: workclub-postgres
+data:
+  init.sql: |
+    -- Create keycloak database and user
+    CREATE DATABASE keycloak;
+    CREATE USER keycloak WITH PASSWORD 'keycloakpass';
+    GRANT ALL PRIVILEGES ON DATABASE keycloak TO keycloak;
+    
+    -- Keycloak database permissions
+    \c keycloak
+    GRANT ALL PRIVILEGES ON SCHEMA public TO keycloak;
+    ALTER SCHEMA public OWNER TO keycloak;
+    
+    -- Application database permissions
+    \c workclub
+    GRANT ALL PRIVILEGES ON SCHEMA public TO app;
+    ALTER SCHEMA public OWNER TO app;