Tab cycles panels within a view; views switch only via F1-F4/Alt+digit

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/ui/help.go

@@ -6,7 +6,8 @@ import (
 )
 
 const helpText = `[yellow]Global[-]
-  F1-F4, Alt+1-4, Tab    switch view
+  F1-F4, Alt+1-4         switch view
+  Tab, Shift+Tab         switch panel within a view
   ?, F9                  this help (F9 works while typing)
   q, Ctrl+C              quit
   Esc                    close dialog / go back
@@ -22,7 +23,6 @@ const helpText = `[yellow]Global[-]
   f                      hide rejected releases
 
 [yellow]Downloads[-]
-  h                      next panel
   p                      pause / resume the SABnzbd queue
   d                      delete the selected job or entry
   b                      remove from arr queue + blocklist