feat(desktop): implement phase 2 native capabilities

frontend/src/components/ThreadComposer.vue

@@ -11,9 +11,12 @@
     <el-input v-model="contentProxy" type="textarea" rows="3" :placeholder="TEXT.common.placeholders.input" />
     <div v-if="allowAttachments" class="upload-row">
       <div class="upload-label">{{ TEXT.common.labels.attachments }}</div>
-      <el-upload v-model:file-list="fileListProxy" :auto-upload="false" multiple list-type="picture" class="thread-upload">
+      <el-upload v-if="!nativeFiles" v-model:file-list="fileListProxy" :auto-upload="false" multiple list-type="picture" class="thread-upload">
         <el-button size="small" class="upload-button">{{ TEXT.common.actions.upload }}</el-button>
       </el-upload>
+      <el-button v-else size="small" class="upload-button" @click="pickNativeAttachments">
+        {{ TEXT.common.actions.upload }}
+      </el-button>
     </div>
     <div class="actions">
       <el-button v-if="showCancel" size="small" @click="$emit('cancel')">{{ TEXT.common.actions.cancel }}</el-button>
@@ -26,6 +29,7 @@
 import { computed } from "vue";
 import type { UploadUserFile } from "element-plus";
 import { displayDateTime, displayUser } from "../utils/display";
+import { clientRuntime, pickFiles } from "../runtime";
 import { TEXT } from "../locales";
 
 const props = defineProps<{
@@ -46,6 +50,7 @@ const emit = defineEmits<{
   (e: "cancel"): void;
   (e: "clear-quote"): void;
 }>();
+const nativeFiles = clientRuntime.capabilities().nativeFiles;
 
 const contentProxy = computed({
   get: () => props.modelValue,
@@ -58,6 +63,21 @@ const fileListProxy = computed({
 });
 
 const quoteContent = (item: any) => (item?.is_deleted ? TEXT.modules.knowledgeMedicalConsult.quoteDeleted : item?.content || TEXT.common.fallback);
+
+const pickNativeAttachments = async () => {
+  const files = await pickFiles({ multiple: true, title: TEXT.common.labels.attachments });
+  const existing = new Set(props.fileList.map((item) => `${item.name}:${item.size}`));
+  const additions: UploadUserFile[] = files
+    .filter((file) => !existing.has(`${file.name}:${file.size}`))
+    .map((file) => ({
+      name: file.name,
+      size: file.size,
+      raw: file as any,
+      status: "ready",
+      uid: Date.now() + Math.floor(Math.random() * 100000),
+    }));
+  emit("update:fileList", [...props.fileList, ...additions]);
+};
 </script>
 
 <style scoped>