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

manifest.json

@@ -2,7 +2,7 @@
    "manifest_version": 3,
    "name": "__MSG_extName__",
    "default_locale": "en",
-   "version": "2026.04.21",
+   "version": "2026.04.22",
    "version_name": "Supports 0.15.0 - 0.27.x",
    "action": {
       "default_popup": "popup.html",