feat: DEVEX-732 premium badging (#27847)

Premium badging and gating consistency

as a OSS user, I want to be upsold to premium, and tastefully

Summary

Standardize all base-Premium full-page gates and the two named inline
notices. Admins see an in-app “Learn about Premium” path; non-admins are
told to contact their deployment administrator.
* DEVEX-732
* updates for premium docs pages for consistency
* updates for premium badging and paywall components
* updates implemented uses of premium badge and premiumpaywall


| Before | After |
| --- | ----------- |
| <img width="1271" height="564" alt="Screenshot 2026-08-04 at 3 02
32 PM"
src="https://github.com/user-attachments/assets/027d4bca-3e34-40b2-ad69-28dbaa4a004b"
/> | <img width="1273" height="600" alt="Screenshot 2026-08-04 at 3 26
37 PM"
src="https://github.com/user-attachments/assets/321083c0-7a4c-4c7e-a19c-059807018d3b"
/> |

| Before | After |
| --- | ----------- |
| <img width="1084" height="672" alt="image"
src="https://github.com/user-attachments/assets/741e6bd9-93b0-4ae0-97df-027e8aba5716"
/> | <img width="1289" height="622" alt="Screenshot 2026-08-04 at 3 20
07 PM"
src="https://github.com/user-attachments/assets/b3a8c169-ca6e-439b-8752-9209131fc097"
/> |

| Before | After |
| --- | ----------- |
| <img width="1091" height="865" alt="image (1)"
src="https://github.com/user-attachments/assets/f7cd92dd-a975-4db0-bc2a-af092ba783ce"
/> | <img width="1268" height="680" alt="Screenshot 2026-08-04 at 3 37
06 PM"
src="https://github.com/user-attachments/assets/8af8081a-0ec9-4fd3-921c-470127f2328b"
/> |

docs/admin/setup/appearance.md

@@ -1,4 +1,4 @@
-# Appearance
+# Appearance (Premium)
 
 > [!NOTE]
 > Customizing Coder's appearance is a Premium feature.