Add Books + editable Recommended Resources sections; improve content block links; v1.1.38

- CustomBlock: add linkUrl/linkLabel fields for a styled button below the body
- Body text auto-linkifies raw URLs into gold anchor tags
- New 'books' placement: Reading List grid on Downloads page (cover, desc, Amazon btn)
- New 'recommended' placement: editable Recommended Resources section on Downloads
  page; falls back to Truth For Life widget when empty
- Admin: Books and Recommended Resources panels added to Content nav

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/content.ts

@@ -26,7 +26,7 @@ export interface CustomLink {
   id: string
   label: string
   url: string
-  placement: 'platforms' | 'footer' | 'resources' | 'otherSites' | 'externalSites'
+  placement: 'platforms' | 'footer' | 'resources' | 'otherSites' | 'externalSites' | 'books' | 'recommended'
   imageUrl?: string
   description?: string
   amazonUrl?: string
@@ -39,6 +39,8 @@ export interface CustomBlock {
   heading: string
   body: string
   page?: 'homepage' | 'start-here' | 'episodes' | 'downloads' | 'about' | 'contact' | 'questions'
+  linkUrl?: string
+  linkLabel?: string
 }
 
 export interface WhereToNextCard {