refactor(sidebar): remove dead directoryStatus probe artifact (#1660)

Commit 7205d7a3 replaced runtime directory probing with buildKnownSessionDirectories

filtering, but left the hook, prop, state, and UI checks as a transitional artifact.

- Delete useDirectoryStatusProbe.ts

- Remove directoryStatus state/prop from SessionSidebar, SessionGroupSection, SessionNodeItem

- Remove isMissingDirectory checks, opacity-75 styling, and disabled states

- Simplify handleSessionSelect signature

- Update sidebar DOCUMENTATION.md

Co-authored-by: Leonid Skorobogatyy <bash@opencode.itc.local>

packages/ui/src/components/session/sidebar/hooks/useSessionActions.ts

@@ -64,11 +64,7 @@ export const useSessionActions = (args: Args) => {
   }, []);
 
   const handleSessionSelect = React.useCallback(
-    (sessionId: string, sessionDirectory?: string | null, disabled?: boolean, projectId?: string | null) => {
-      if (disabled) {
-        return;
-      }
-
+    (sessionId: string, sessionDirectory?: string | null, projectId?: string | null) => {
       const resetSessionSearch = () => {
         if (!args.isSessionSearchOpen && args.sessionSearchQuery.length === 0) {
           return;