data(emoji): every Japanese alias in both kana

A query typed in the Hiragana mode is hiragana; CLDR's Japanese
keywords are mostly katakana (スマイル, ハート), so the one could not
find the other.  mkemoji now writes each alias that has kana in both
scripts.

map/README

@@ -45,8 +45,10 @@ so that a bare `1`-`9` picks the matching superscript or subscript from a
 `^` or `_` prefix search.  `emoji.src` is generated: every fully-qualified
 emoji of Unicode's `emoji-test.txt` except the skin-tone variants, with
 its CLDR names and keywords in English, Korean, and Japanese.  `mkemoji`
-folds the aliases and writes one row per alias to `emoji.dict`; the engine
+folds the aliases, adds each Japanese one in the other kana so a query
-searches that dictionary by prefix, so the rows carry no prefixes.
+typed in either mode finds it, and writes one row per alias to
+`emoji.dict`; the engine searches that dictionary by prefix, so the rows
+carry no prefixes.
 
 The sources are Emoji 17.0 and CLDR 48.2.0.  Regenerate them from the
 repository root with:

map/mkemoji

@@ -12,11 +12,21 @@ MAXRUNES = 64
 MAXCANDIDATES = 128
 
 
+HIRA = {c: c + 0x60 for c in range(0x3041, 0x3097)}
+KATA = {c: c - 0x60 for c in range(0x30A1, 0x30F7)}
+
+
 def fold(s):
     s = "".join(chr(ord(c) + 32) if "A" <= c <= "Z" else c for c in s)
     return unicodedata.normalize("NFC", s)
 
 
+def kana(alias):
+    """The alias, and in the other kana where it has any: a query typed
+    in either Japanese mode finds it."""
+    return {alias, alias.translate(HIRA), alias.translate(KATA)}
+
+
 def hascontrol(s):
     return any(unicodedata.category(c) == "Cc" for c in s)
 
@@ -42,7 +52,7 @@ def read(path):
                 if (not alias or len(alias) > MAXRUNES or hascontrol(alias)
                         or alias != alias.strip() or alias.startswith(";")):
                     raise ValueError(f"{path}:{lineno}: bad alias")
-                entries.append((result, alias))
+                entries.extend((result, a) for a in sorted(kana(alias)))
     return entries