fix: make step 1 clicks show connector lines like other steps

Previously clicking a step 1 block would set it as an entry point filter
instead of showing connection lines. Now all steps behave consistently —
clicking any step toggles selection and draws connector lines to the next
column. Entry point filtering remains available via the dropdown.

app/sites/[id]/journeys/page.tsx

@@ -190,7 +190,6 @@ export default function JourneysPage() {
             transitions={transitionsData?.transitions ?? []}
             totalSessions={totalSessions}
             depth={committedDepth}
-            onNodeClick={(path) => setEntryPath(path)}
           />
         </div>