feat(reader): serialize and coordinate sync jobs in KOReader plugin

Introduce a sync coordinator to serialize and prioritize KOReader sync jobs (such as progress sync, highlight sync, library sweep, and update check). Coalesce pending jobs by family to prevent race conditions and redundant network requests. Use a dedicated scheduler for open annotations to handle highlight sync and matching asynchronously on book open. Add a diagnostics menu in the settings to track detailed sync status and provide clear error messages for debugging.

client/src/components/AppSidebar.vue

@@ -33,6 +33,7 @@ import { useThemeStore } from '@/stores/theme'
 import { useAppInfo } from '@/features/settings/composables/useAppInfo'
 import { buildSidebarVersionUi } from '@/components/sidebar/versionUi'
 import { useWhatsNew } from '@/features/whats-new/composables/useWhatsNew'
+import { Tooltip, TooltipContent, TooltipTrigger } from '@/components/ui/tooltip'
 
 function useSidebarSection(key: string) {
   const isOpen = ref(localStorage.getItem(`bookorbit:sidebar:${key}`) !== 'false')
@@ -55,6 +56,7 @@ const { handleLibraryCreated } = useLibraryCreationRedirect()
 const themeStore = useThemeStore()
 const { version, updateAvailable, latestVersion, loadAppInfo } = useAppInfo()
 const { hasUnseen: hasUnseenWhatsNew } = useWhatsNew()
+const supportUrl = 'https://ko-fi.com/neonbookorbit'
 
 const iconRadiusClass = computed(() => (themeStore.radius === 'sharp' ? 'rounded-none' : 'rounded-full'))
 const versionUi = computed(() => {
@@ -438,14 +440,50 @@ onUnmounted(() => stopLibraryUploadListener())
       </SidebarGroup>
     </SidebarContent>
 
-    <SidebarFooter v-if="versionUi.currentLabel" class="border-t border-sidebar-border/60">
+    <SidebarFooter class="border-t border-sidebar-border/60">
+      <div class="hidden justify-center group-data-[collapsible=icon]:flex">
+        <Tooltip>
+          <TooltipTrigger as-child>
+            <a
+              :href="supportUrl"
+              target="_blank"
+              rel="noopener noreferrer"
+              aria-label="Support BookOrbit on Ko-fi"
+              class="inline-flex h-8 w-8 items-center justify-center rounded-lg border border-sidebar-border/60 text-primary transition-colors hover:bg-primary/8 hover:text-primary/85 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-sidebar-ring"
+            >
+              <Icons.Heart class="h-4 w-4 fill-primary/20" aria-hidden="true" />
+            </a>
+          </TooltipTrigger>
+          <TooltipContent side="right">Support BookOrbit</TooltipContent>
+        </Tooltip>
+      </div>
+
       <div class="px-2 py-2 group-data-[collapsible=icon]:hidden">
-        <div class="flex flex-wrap items-center justify-center gap-2 text-center text-[12px] font-medium leading-none text-sidebar-foreground/80">
-          <RouterLink to="/whats-new" class="inline-flex items-center gap-1.5 transition-colors hover:text-sidebar-foreground">
-            {{ versionUi.currentLabel }}
-            <span v-if="hasUnseenWhatsNew" class="h-1.5 w-1.5 rounded-full bg-primary" aria-label="New release notes available" />
+        <div
+          class="flex min-w-0 flex-wrap items-center justify-center gap-x-2 gap-y-1 text-center text-[12px] font-medium leading-none text-sidebar-foreground/80"
+        >
+          <RouterLink
+            v-if="versionUi.currentLabel"
+            to="/whats-new"
+            class="inline-flex min-w-0 max-w-full items-center gap-1.5 transition-colors hover:text-sidebar-foreground"
+          >
+            <span class="truncate">{{ versionUi.currentLabel }}</span>
+            <span v-if="hasUnseenWhatsNew" class="h-1.5 w-1.5 flex-none rounded-full bg-primary" aria-label="New release notes available" />
           </RouterLink>
 
+          <span v-if="versionUi.currentLabel" class="text-sidebar-foreground/45">•</span>
+
+          <a
+            :href="supportUrl"
+            target="_blank"
+            rel="noopener noreferrer"
+            aria-label="Support BookOrbit on Ko-fi"
+            class="inline-flex shrink-0 items-center gap-1.5 text-sidebar-foreground/85 transition-colors hover:text-primary"
+          >
+            <Icons.Heart class="h-3.5 w-3.5 fill-primary/20 text-primary" aria-hidden="true" />
+            <span>Support</span>
+          </a>
+
           <span v-if="versionUi.showLatest" class="text-sidebar-foreground/45">•</span>
 
           <a
@@ -453,9 +491,9 @@ onUnmounted(() => stopLibraryUploadListener())
             :href="versionUi.latestHref"
             target="_blank"
             rel="noopener noreferrer"
-            class="font-semibold text-primary transition-colors hover:text-primary/85"
+            class="inline-flex min-w-0 max-w-full font-semibold text-primary transition-colors hover:text-primary/85"
           >
-            Latest {{ versionUi.latestLabel }}
+            <span class="truncate">Latest {{ versionUi.latestLabel }}</span>
           </a>
         </div>
       </div>