feat: improve i18n support as a whole (#1526)

* feat: improve i18n support as a whole

- Remove dayjs in favor of /helpers/datetime.ts, which uses
Intl.DateTimeFormat and Date. Dayjs is not exactly i18n friendly
and has several locale related opened issues.

- Move/refactor date/time code from /helpers/utils.ts to
/helpers/datetime.ts.

- Fix Daily Review weekday not changing according to selected date.

- Localize Daily review weekday and month.

- Load i18n listed strings from /locales/{locale}.json in a dynamic way.
This makes much easier to add new locales, by just adding a properly
named json file and listing it only in /web/src/i18n.ts and
/api/user_setting.go.

- Fallback languages are now set in /web/src/i18n.ts.

- Full language codes are now preffered, but they fallback to 2-letter
codes when not available.

- The locale dropdown is now populated dynamically from the available
locales. Locale names are populated by the browser via
Intl.DisplayNames(locale).

- /web/src/i18n.ts now exports a type TLocale from availableLocales
array. This is used only by findNearestLanguageMatch(). As I was unable
to use this type in ".d.ts" files, I switched the Locale type from
/web/src/types/i18n.d.ts to string.

- Move pretty much all hardcoded text strings to i18n strings.

- Add pt-BR translation.

- Remove site.ts and move its content to a i18n string.

- Rename zh.json to zh-Hans.json to get the correct language name on
selector dropdown.

- Remove pt_BR.json and replace with pt-BR.json.

- Some minor layout spacing fixes to accommodate larger texts.

- Improve some error messages.

* Delete .yarnrc.yml

* Delete package-lock.json

* fix: 158:28  error  Insert `⏎`  prettier/prettier

web/src/components/Memo.tsx

@@ -1,4 +1,4 @@
-import dayjs from "dayjs";
+import { getRelativeTimeString } from "@/helpers/datetime";
 import { memo, useEffect, useRef, useState } from "react";
 import { toast } from "react-hot-toast";
 import { useTranslation } from "react-i18next";
@@ -19,14 +19,6 @@ interface Props {
   readonly?: boolean;
 }
 
-export const getFormatedMemoTimeStr = (time: number, locale = "en"): string => {
-  if (Date.now() - time < 1000 * 60 * 60 * 24) {
-    return dayjs(time).locale(locale).fromNow();
-  } else {
-    return dayjs(time).locale(locale).format("YYYY/MM/DD HH:mm:ss");
-  }
-};
-
 const Memo: React.FC<Props> = (props: Props) => {
   const { memo, readonly } = props;
   const { t, i18n } = useTranslation();
@@ -35,7 +27,7 @@ const Memo: React.FC<Props> = (props: Props) => {
   const filterStore = useFilterStore();
   const userStore = useUserStore();
   const memoStore = useMemoStore();
-  const [createdTimeStr, setCreatedTimeStr] = useState<string>(getFormatedMemoTimeStr(memo.createdTs, i18n.language));
+  const [createdTimeStr, setCreatedTimeStr] = useState<string>(getRelativeTimeString(memo.createdTs));
   const memoContainerRef = useRef<HTMLDivElement>(null);
   const isVisitorMode = userStore.isVisitorMode() || readonly;
 
@@ -43,7 +35,7 @@ const Memo: React.FC<Props> = (props: Props) => {
     let intervalFlag: any = -1;
     if (Date.now() - memo.createdTs < 1000 * 60 * 60 * 24) {
       intervalFlag = setInterval(() => {
-        setCreatedTimeStr(getFormatedMemoTimeStr(memo.createdTs, i18n.language));
+        setCreatedTimeStr(getRelativeTimeString(memo.createdTs));
       }, 1000 * 1);
     }
 
@@ -90,8 +82,8 @@ const Memo: React.FC<Props> = (props: Props) => {
 
   const handleDeleteMemoClick = async () => {
     showCommonDialog({
-      title: "Delete memo",
-      content: "Are you sure to delete this memo?",
+      title: t("memo.delete-memo"),
+      content: t("memo.delete-confirm"),
       style: "warning",
       dialogName: "delete-memo-dialog",
       onConfirm: async () => {