Fix large clipboard history pastes

Clipboard history selections passed the full selected text as a process argument to omarchy-clipboard-paste-text. Large entries can exceed Linux's per-argument exec limit, so the helper never starts reliably for big copied blocks.

Pass the original history index instead and have the helper read that entry from clipboard-history.json before wl-copy and Shift+Insert. Also focus the first row when opening the manager, keep filtered rows mapped to their original history indexes, and drop whitespace-only text entries.

shell/plugins/clipboard/Clipboard.qml

@@ -40,7 +40,7 @@ Item {
     root.opened = true
     root.filterText = ""
     root.selectedIndex = 0
-    root.cursorActive = false
+    root.cursorActive = true
     root.rebuildDisplay()
     Qt.callLater(function() { keyCatcher.forceActiveFocus() })
   }
@@ -140,7 +140,7 @@ Item {
     if (row.entryType === "image") {
       Quickshell.execDetached([root.omarchyPath + "/bin/omarchy-clipboard-paste-file", row.mime, row.path])
     } else if (row.fullText) {
-      Quickshell.execDetached([root.omarchyPath + "/bin/omarchy-clipboard-paste-text", "--shift-insert", row.fullText])
+      Quickshell.execDetached([root.omarchyPath + "/bin/omarchy-clipboard-paste-text", "--shift-insert", "--history-index", String(row.index)])
     }
   }