feat: add screenshot OCR extraction

frontend/src/App.vue

@@ -23,6 +23,7 @@ import {
   SaveRegionImage,
   SaveRegionToRemote,
   SummarizeRegion,
+  ExtractTextRegion,
   CancelRegion,
   GetConfig,
 } from '../wailsjs/go/main/App'
@@ -58,7 +59,7 @@ async function loadThemePreference() {
 // `SettingsTab` is hoisted to the App shell so the sidebar (which lives
 // here) and the inner SettingsView (which renders the matching card) can
 // share a single source of truth without an event bus.
-type SettingsTab = 'general' | 's3' | 'ssh' | 'llm'
+type SettingsTab = 'general' | 's3' | 'ssh' | 'llm' | 'ocr'
 const activeTab = ref<SettingsTab>('general')
 
 // Sidebar entries are declarative so adding a destination type later is
@@ -68,6 +69,7 @@ const sidebarItems: Array<{ id: SettingsTab; label: string }> = [
   { id: 's3', label: '对象存储' },
   { id: 'ssh', label: '远程主机' },
   { id: 'llm', label: '智能识图' },
+  { id: 'ocr', label: '文字提取' },
 ]
 
 interface OverlayPayload {
@@ -192,6 +194,16 @@ async function onOverlaySummarize(rect: OverlayResult) {
   }
 }
 
+async function onOverlayOCR(rect: OverlayResult) {
+  mode.value = 'settings'
+  overlayPayload.value = null
+  try {
+    await ExtractTextRegion(rect as any)
+  } catch {
+    /* Surfaced via upload:failure */
+  }
+}
+
 async function onOverlayCancel() {
   mode.value = 'settings'
   overlayPayload.value = null
@@ -223,6 +235,8 @@ onMounted(() => {
       'success',
       url === 'summary copied to clipboard'
         ? 'Summary copied to clipboard'
+        : url === 'ocr text copied to clipboard'
+          ? 'OCR text copied to clipboard'
         : `Copied: ${url}`
     )
   })
@@ -262,6 +276,7 @@ onUnmounted(() => {
     @save="onOverlaySave"
     @save-remote="onOverlaySaveRemote"
     @summarize="onOverlaySummarize"
+    @ocr="onOverlayOCR"
     @cancel="onOverlayCancel"
   />