feat: surface orphaned high-value onboarding content

Navigation improvements:
- Add "What is Last Click Attribution" to FAQs (key concept users search for)
- Fix filename typo: attribuion → attribution
- Update related article links to internal paths

Onboarding tab expansion:
- Add intro-to-sm and why-source-medium at start of Getting Started
- Add level-3-data-checklist to complete the progression
- Create new "Account Management" group with:
  - how-to-manage-user-access
  - creating-google-groups
  - sharing-access

This surfaces ~20KB of valuable existing content that was orphaned
(existed in filesystem but not in navigation).

Author: lordhumunguz

docs.json

@@ -26,6 +26,7 @@
               {
                 "group": "Data Clarification & Discrepancies",
                 "pages": [
+                  "help-center/faq/account-management-faqs/what-is-last-click-attribution",
                   "help-center/faq/data-faqs/why-would-external-reports-not-match-the-sourcemedium-dashboard",
                   "help-center/faq/data-faqs/why-dont-the-executive-summary-and-shopifys-sales-report-match",
                   "help-center/faq/data-faqs/why-isnt-the-executive-summary-report-attributing-my-gift-card-revenue",
@@ -85,9 +86,12 @@
           {
             "group": "Getting Started",
             "pages": [
+              "onboarding/getting-started/intro-to-sm",
+              "onboarding/getting-started/why-source-medium",
               "onboarding/getting-started/getting-started-checklist",
               "onboarding/getting-started/level-1-data-checklist",
               "onboarding/getting-started/level-2-data-checklist",
+              "onboarding/getting-started/level-3-data-checklist",
               "onboarding/getting-started/how-to-work-with-the-sourcemedium-team",
               {
                 "group": "The Analytical Mindset",
@@ -98,6 +102,14 @@
               }
             ]
           },
+          {
+            "group": "Account Management",
+            "pages": [
+              "onboarding/getting-started/how-to-manage-user-access",
+              "onboarding/analytics-tools/creating-google-groups",
+              "onboarding/analytics-tools/sharing-access"
+            ]
+          },
           {
             "group": "Analytics Tools",
             "pages": [

…t-faqs/what-is-last-click-attribuion.mdx …-faqs/what-is-last-click-attribution.mdxhelp-center/faq/account-management-faqs/what-is-last-click-attribuion.mdx renamed to help-center/faq/account-management-faqs/what-is-last-click-attribution.mdx help-center/faq/account-management-faqs/what-is-last-click-attribuion.mdx renamed to help-center/faq/account-management-faqs/what-is-last-click-attribution.mdx

@@ -39,12 +39,19 @@ In addition, we stitch GA data with Shopify data to get the best UTM coverage an
 
 Last click attribution has the least likelihood of breaking compared to the other stages of tracking. When combined with information like a post purchase survey, last click attribution can help you understand a customer's journey of where they found your company and what marketing channels they were influenced by.
 
-### Related Articles: 
-
-[How can I improve my last-click UTM attribution?](https://help.sourcemedium.com/articles/how-can-i-improve-my-last-click-utm-attribution) 
-
-[Do you have a proper Google Analytics setup?](https://help.sourcemedium.com/articles/do-you-have-a-proper-google-analytics-setup) 
-
-[Are you utilizing customer and order tagging for deeper enrichment of your data?](https://help.sourcemedium.com/articles/are-you-utilizing-customer-and-order-tagging-for-deeper-enrichment-of-your-data)
-
-[What attribution windows does SourceMedium report on for marketing platforms?](https://help.sourcemedium.com/articles/what-attribution-windows-does-source-medium-report-on-for-marketing-platforms)
+### Related Articles
+
+<CardGroup cols={2}>
+  <Card title="Improve Last-Click Attribution" icon="bullseye" href="/help-center/faq/account-management-faqs/how-can-i-improve-my-last-click-attribution">
+    Best practices for UTM tracking hygiene.
+  </Card>
+  <Card title="Customer & Order Tagging" icon="tags" href="/help-center/faq/account-management-faqs/are-you-utilizing-customer-and-order-tagging-for-deeper-enrichment-of-your-data">
+    Enrich your data with zero-party attribution.
+  </Card>
+  <Card title="Attribution Windows" icon="clock" href="/help-center/faq/data-faqs/what-attribution-windows-does-sourcemedoum-report-on-for-marketing-platforms">
+    How SourceMedium reports platform attribution windows.
+  </Card>
+  <Card title="Attribution Health" icon="heart-pulse" href="/data-inputs/attribution-health">
+    Strategies for improving attribution coverage.
+  </Card>
+</CardGroup>