Decouple node help between sidebar and right panel (#8110)

## Summary

When the node library is open and you click on the node toolbar info
button, this causes the node library info panel & right panel node info
to show the same details.

## Changes

- Extract useNodeHelpContent composable so NodeHelpContent fetches its
own content, allowing multiple panels to show help independently
- Remove sync behavior from NodeHelpPage that caused left sidebar to
change when selecting different graph nodes since we want to prioritise
right panel for this behavior
- Add telemetry tracking for node library help button to identify how
frequently this is used

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8110-Decouple-node-help-between-sidebar-and-right-panel-2ea6d73d365081a9b3afd25aa51b34bd)
by [Unito](https://www.unito.io)

src/composables/useNodeHelpContent.ts

@@ -0,0 +1,79 @@
+import type { MaybeRefOrGetter } from 'vue'
+import { computed, ref, toValue, watch } from 'vue'
+import { useI18n } from 'vue-i18n'
+
+import { nodeHelpService } from '@/services/nodeHelpService'
+import type { ComfyNodeDefImpl } from '@/stores/nodeDefStore'
+import { renderMarkdownToHtml } from '@/utils/markdownRendererUtil'
+import { getNodeHelpBaseUrl } from '@/workbench/utils/nodeHelpUtil'
+
+/**
+ * Composable for fetching and rendering node help content.
+ * Creates independent state for each usage, allowing multiple panels
+ * to show help content without interfering with each other.
+ *
+ * @param nodeRef - Reactive reference to the node to show help for
+ * @returns Reactive help content state and rendered HTML
+ */
+export function useNodeHelpContent(
+  nodeRef: MaybeRefOrGetter<ComfyNodeDefImpl | null>
+) {
+  const { locale } = useI18n()
+
+  const helpContent = ref<string>('')
+  const isLoading = ref<boolean>(false)
+  const error = ref<string | null>(null)
+
+  let currentRequest: Promise<string> | null = null
+
+  const baseUrl = computed(() => {
+    const node = toValue(nodeRef)
+    if (!node) return ''
+    return getNodeHelpBaseUrl(node)
+  })
+
+  const renderedHelpHtml = computed(() => {
+    return renderMarkdownToHtml(helpContent.value, baseUrl.value)
+  })
+
+  // Watch for node changes and fetch help content
+  watch(
+    () => toValue(nodeRef),
+    async (node) => {
+      helpContent.value = ''
+      error.value = null
+
+      if (node) {
+        isLoading.value = true
+        const request = (currentRequest = nodeHelpService.fetchNodeHelp(
+          node,
+          locale.value || 'en'
+        ))
+
+        try {
+          const content = await request
+          if (currentRequest !== request) return
+          helpContent.value = content
+        } catch (e: unknown) {
+          if (currentRequest !== request) return
+          error.value = e instanceof Error ? e.message : String(e)
+          helpContent.value = node.description || ''
+        } finally {
+          if (currentRequest === request) {
+            currentRequest = null
+            isLoading.value = false
+          }
+        }
+      }
+    },
+    { immediate: true }
+  )
+
+  return {
+    helpContent,
+    isLoading,
+    error,
+    baseUrl,
+    renderedHelpHtml
+  }
+}