feat: resolve 7 pre-ship QoL items

- Space/Shift+Space: page down/up in detail panel (80% scroll)
- Content font: sans-serif/serif/monospace selector in appearance
  settings, applied to article content in detail panel
- Accessibility: entry-list-item uses button instead of div, folder
  toggles have aria-expanded, shortcut keys have aria-labels
- Share notes: replaced window.prompt with proper modal dialog
  matching existing UI patterns
- Worker .env.example: template with all 10 environment variables
- Worker poisoned messages: archive unprocessable queue messages
  instead of leaving them stuck forever
- Worker pool Submit: check return value, reschedule dropped feeds
  30s into the future, log warnings for rejected submissions

1 files changed, 14 insertions, 0 deletions

diff --git a/apps/web/lib/hooks/use-keyboard-navigation.ts b/apps/web/lib/hooks/use-keyboard-navigation.ts
index 24a4761..8685396 100644
--- a/apps/web/lib/hooks/use-keyboard-navigation.ts
+++ b/apps/web/lib/hooks/use-keyboard-navigation.ts
@@ -368,6 +368,7 @@ export function useKeyboardNavigation() {
 
     function handleDetailPanelKeyDown(event: KeyboardEvent) {
       const SCROLL_AMOUNT = 100
+      const PAGE_SCROLL_FRACTION = 0.8
       const detailArticle = document.querySelector<HTMLElement>(
         "[data-detail-article]"
       )
@@ -385,6 +386,19 @@ export function useKeyboardNavigation() {
           if (detailArticle) detailArticle.scrollTop -= SCROLL_AMOUNT
           break
         }
+        case " ": {
+          event.preventDefault()
+          if (detailArticle) {
+            const pageScrollAmount =
+              detailArticle.clientHeight * PAGE_SCROLL_FRACTION
+            if (event.shiftKey) {
+              detailArticle.scrollTop -= pageScrollAmount
+            } else {
+              detailArticle.scrollTop += pageScrollAmount
+            }
+          }
+          break
+        }
         case "?": {
           event.preventDefault()
           toggleShortcutsDialog()