fix: standardize i18n pluralization to two-part English format (#9384)

## Summary

Standardize 5 English pluralization strings from incorrect 3-part format
to proper 2-part `"singular | plural"` format.

## Changes

- **What**: Convert `nodesCount`, `asset`, `errorCount`,
`downloadsFailed`, and `exportFailed` i18n keys from redundant 3-part
pluralization (zero/one/many) to standard 2-part English format
(singular/plural)

## Review Focus

The 3-part format (`a | b | a`) was redundant for English since the
first and third parts were identical. vue-i18n only needs 2 parts for
English pluralization.

Fixes #9277

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9384-fix-standardize-i18n-pluralization-to-two-part-English-format-3196d73d365081cf97c4e7cfa310ce8e)
by [Unito](https://www.unito.io)

src/locales/en/main.json

@@ -178,7 +178,7 @@
     "uploadAlreadyInProgress": "Upload already in progress",
     "capture": "capture",
     "nodes": "Nodes",
-    "nodesCount": "{count} nodes | {count} node | {count} nodes",
+    "nodesCount": "{count} node | {count} nodes",
     "addNode": "Add a node...",
     "filterBy": "Filter by:",
     "filterByType": "Filter by {type}...",
@@ -222,7 +222,7 @@
     "failed": "Failed",
     "cancelled": "Cancelled",
     "job": "Job",
-    "asset": "{count} assets | {count} asset | {count} assets",
+    "asset": "{count} asset | {count} assets",
     "untitled": "Untitled",
     "emDash": "—",
     "enabling": "Enabling {id}",
@@ -3347,7 +3347,7 @@
     }
   },
   "errorOverlay": {
-    "errorCount": "{count} ERRORS | {count} ERROR | {count} ERRORS",
+    "errorCount": "{count} ERROR | {count} ERRORS",
     "seeErrors": "See Errors"
   },
   "help": {
@@ -3357,7 +3357,7 @@
   "progressToast": {
     "importingModels": "Importing Models",
     "downloadingModel": "Downloading model...",
-    "downloadsFailed": "{count} downloads failed | {count} download failed | {count} downloads failed",
+    "downloadsFailed": "{count} download failed | {count} downloads failed",
     "allDownloadsCompleted": "All downloads completed",
     "noImportsInQueue": "No {filter} in queue",
     "failed": "Failed",
@@ -3374,7 +3374,7 @@
     "exportingAssets": "Exporting Assets",
     "preparingExport": "Preparing export...",
     "exportError": "Export failed",
-    "exportFailed": "{count} export failed | {count} export failed | {count} exports failed",
+    "exportFailed": "{count} export failed | {count} exports failed",
     "allExportsCompleted": "All exports completed",
     "noExportsInQueue": "No {filter} exports in queue",
     "exportStarted": "Preparing ZIP download...",