docs(admin): admin-guide front door + Administration area in the portal

The tenth and final page: the section directory with one-line coverage
per page, the fresh-instance quick path (libraries -> scan -> Base URL
-> users -> devices), and the when-something-looks-wrong triage table
mapping symptoms to pages. The portal (index.md) gains a For
Administrators area listing all nine admin pages; the user guide's
'being expanded separately' line becomes the done-state sentence.
Every control name quoted here exists in the glossary.

docs/index.md

@@ -32,7 +32,21 @@ Complete guide to Bookhoard documentation. Find what you need quickly.
   - [Themes](user/themes.md)
   - [Calibre Integration](user/calibre-integration.md)
   - [Profile Guide](user/profile-guide.md)
-  - [Admin Guide](admin/admin-guide.md)
+
+### 🛡 For Administrators
+
+**[Admin Guide](admin/admin-guide.md)** - running a Bookhoard instance: every admin page, what each control actually does
+
+- **Administration**
+  - [Admin Dashboard](admin/dashboard.md) - stats, Force Rescan All Libraries, scan progress
+  - [Libraries](admin/libraries.md) - create libraries, folders, user access, scanning
+  - [Processing Issues](admin/library-processing-issues.md) - items the scanner couldn't process
+  - [Archived Items](admin/archived-items.md) - missing files, history-preserving archive
+  - [All Podcasts](admin/podcasts.md) - the maintenance view for every feed
+  - [Hash Conflicts](admin/hash-conflicts.md) - duplicate content resolution
+  - [Users](admin/users.md) - accounts, roles, password resets
+  - [System Settings](admin/settings.md) - every setting: key, default, range, meaning
+  - [Scanning](admin/scanning.md) - shallow vs. force: what every scan button does
 
 ### 👨‍💻 For Developers