Add Memos API adapter and settings UI

Introduce a Memos API adapter to unify compatibility across API flavors (v020-v021, v023, modern) and probe/detect server flavor. Add js/compat/memosApi.adapter.js and rename existing compat modules (memosApi.v024.js -> memosApi.modern.js, memosApi.v1.js -> memosApi.v020-v021.js) and trim probe from v023. Add settings UI support: new i18n keys in en/ja/ko/zh_CN, settings panel styles in css/main.css, new settings input binding and save flow in js (attachment-only default text persisted). Refactor oper.js to use the adapter for uploads, deletes, tag listing, search and image preview auth handling; add helper functions for attachment-only default text and settings payload. Update i18n bindings, popup, manifest and README changelog accordingly.
closed #5

_locales/en/messages.json

@@ -23,6 +23,18 @@
    "supportedMemosVersion": {
       "message": "Compatible with Memos v0.15.0 - 0.27.x"
    },
+   "settingsConnectionTitle": {
+      "message": "Connection"
+   },
+   "settingsConnectionDesc": {
+      "message": "Configure the Memos site URL and access token."
+   },
+   "settingsPostingTitle": {
+      "message": "Posting"
+   },
+   "settingsPostingDesc": {
+      "message": "Default text for attachment-only sends"
+   },
    "placeApiUrl":{
       "message": "Memos site URL"
    },
@@ -50,6 +62,9 @@
    "placeShowInput":{
       "message": "Default 'Everyone can see' Tag name"
    },
+   "placeAttachmentOnlyDefaultText": {
+      "message": "Default text for attachment-only sends (leave blank to use built-in text)"
+   },
    "uploadedListTitle": {
       "message": "Uploaded files, Drag to reorder"
    },

_locales/ja/messages.json

@@ -23,6 +23,18 @@
   "supportedMemosVersion": {
     "message": "Memos v0.15.0 - 0.27.x に対応"
   },
+  "settingsConnectionTitle": {
+    "message": "接続設定"
+  },
+  "settingsConnectionDesc": {
+    "message": "Memos のURLとアクセストークンを設定します。"
+  },
+  "settingsPostingTitle": {
+    "message": "投稿設定"
+  },
+  "settingsPostingDesc": {
+    "message": "添付ファイルのみ送信時の既定テキスト"
+  },
   "placeApiUrl": {
     "message": "Memos サイトURL"
   },
@@ -50,6 +62,9 @@
   "placeShowInput": {
     "message": "既定の「全員に公開」タグ名"
   },
+  "placeAttachmentOnlyDefaultText": {
+    "message": "添付ファイルのみ送信時の既定テキスト（空欄で内蔵文言を使用）"
+  },
   "uploadedListTitle": {
     "message": "アップロード済みファイル（ドラッグで並べ替え）"
   },

_locales/ko/messages.json

@@ -23,6 +23,18 @@
   "supportedMemosVersion": {
     "message": "Memos v0.15.0 - 0.27.x 호환"
   },
+  "settingsConnectionTitle": {
+    "message": "연결 설정"
+  },
+  "settingsConnectionDesc": {
+    "message": "Memos 사이트 URL과 액세스 토큰을 설정합니다."
+  },
+  "settingsPostingTitle": {
+    "message": "전송 설정"
+  },
+  "settingsPostingDesc": {
+    "message": "첨부만 전송할 때의 기본 텍스트"
+  },
   "placeApiUrl": {
     "message": "Memos 사이트 URL"
   },
@@ -50,6 +62,9 @@
   "placeShowInput": {
     "message": "기본 '모두 공개' 태그 이름"
   },
+  "placeAttachmentOnlyDefaultText": {
+    "message": "첨부만 전송할 때의 기본 텍스트(비워두면 내장 문구 사용)"
+  },
   "uploadedListTitle": {
     "message": "업로드된 파일(드래그로 순서 변경)"
   },

_locales/zh_CN/messages.json

@@ -23,6 +23,18 @@
    "supportedMemosVersion": {
       "message": "兼容 Memos v0.15.0 - 0.27.x"
    },
+   "settingsConnectionTitle": {
+      "message": "连接设置"
+   },
+   "settingsConnectionDesc": {
+      "message": "配置 Memos 服务地址和访问令牌。"
+   },
+   "settingsPostingTitle": {
+      "message": "发送设置"
+   },
+   "settingsPostingDesc": {
+      "message": "仅发送附件时的默认文本"
+   },
    "placeApiUrl":{
       "message": "请填入 Memos 主页网址"
    },
@@ -50,6 +62,9 @@
    "placeShowInput":{
       "message": "默认“公开”标签名"
    },
+   "placeAttachmentOnlyDefaultText":{
+      "message": "仅发送附件时的默认文本（留空则使用内置文案）"
+   },
    "picDrag":{
       "message": "拖拽到窗口上传该图片"
    },