feat: WeKan ticketing source

- wekan connector: board id as project key, cards assigned to the
  consultant's WeKan username (assignees with member fallback), archived
  cards skipped, client-side modifiedAt since-filtering, username/password
  login with token reuse (or pre-issued token), case-insensitive identity
- fake-WeKan unit tests: factory validation, test-connection, fetch
  filtering, key listing, token reuse
- admin customer wizard: WeKan option + credential fields
- OpenAPI enum + credential shapes, README identity mapping docs

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

internal/sync/connector.go

@@ -71,6 +71,23 @@ func NewConnector(t domain.TicketingType, baseURL, projectKey string, creds Cred
 			return nil, fmt.Errorf("youtrack requires permanentToken")
 		}
 		return &youtrackConnector{baseURL: baseURL, projectKey: projectKey, token: creds["permanentToken"]}, nil
+	case domain.TicketingWekan:
+		hasLogin := creds["username"] != "" && creds["password"] != ""
+		hasToken := creds["token"] != ""
+		if !hasLogin && !hasToken {
+			return nil, fmt.Errorf("wekan requires username+password (or a pre-issued token)")
+		}
+		if baseURL == "" {
+			return nil, fmt.Errorf("wekan requires baseUrl")
+		}
+		if projectKey == "" {
+			return nil, fmt.Errorf("wekan requires projectKey (the board id)")
+		}
+		return &wekanConnector{
+			baseURL: baseURL, boardID: projectKey,
+			username: creds["username"], password: creds["password"],
+			token: creds["token"],
+		}, nil
 	case domain.TicketingDemo:
 		return &demoConnector{projectKey: projectKey}, nil
 	default: