data(hanja): a lone consonant is a reading too

Every Korean keyboard's 한자 key answers a lone consonant with the KS X
1001 symbol palette, and has since 한글 워드프로세서: ㅁ for ※ ○ △ ㈜, ㄴ
for the brackets, ㄹ for the units, ㅇ for the circled numbers.  strans
sends that key to the same search as a syllable -- Khanja is Ctrl+H at
strans.c:830, and startsearch seeds the query with whatever ko.c left
pending -- but every one of hanja.dict's 187286 readings is a syllable, so
the popup came up with a query in it and nothing to pick:

	ㅁ: 0 candidates
	ㄴ: 0 candidates
	ㄹ: 0 candidates
	한: 99 candidates 韓 漢 寒 限 閑 恨 旱 汗 翰 邯 罕 悍 澣 閒 瀚

libhangul ships that palette beside the Hanja table already imported here:
data/hanja/mssymbol.txt, same commit, same author, same BSD-3 terms, same
key:value:comment format -- and keyed by the compatibility jamo ko.c
already holds, U+3141 for ㅁ.  So the engine does not change at all; the
same dictlookup on the same trie now finds something:

	ㅁ: 75 candidates ＃ ＆ ＊ ＠ § ※ ☆ ★ ○ ● ◎ ◇ ◆ □ ■ △ ▲ ▽ ▼
	ㄴ: 23 candidates ＂ （ ） ［ ］ ｛ ｝ ‘ ’ “ ” 〔 〕 〈 〉 《 》 「 」
	ㄹ: 94 candidates ＄ ％ ￦ Ｆ ′ ″ ℃ Å ￠ ￡ ￥ ¤ ℉ ‰ € ㎕ ㎖ ㎗ ℓ
	한: 99 candidates 韓 漢 寒 限 閑 恨 旱 汗 翰 邯 罕 悍 澣 閒 瀚

Both scripts widen by one rule -- a syllable reading gives Hanja, a jamo
reading gives a symbol -- and hanja.src regenerates byte for byte as it
was, because upstream's own non-syllable readings are words like ㄱ자집
whose values were never Hanja and still fall out.  985 of mssymbol.txt's
987 rows survive: its ideographic space and its soft hyphen do not, since
a candidate the popup cannot draw is not a candidate, and the row format
separates candidates with a space besides.

The two keyspaces cannot collide -- one is syllables, one is single jamo --
so the 187286 existing rows are unchanged, byte for byte, and 18 rows join
them.  mkhanja takes a source list as mkemoji already does, and keeps each
upstream header, which is why the licence text now appears twice.

89 unit, check-live, check-stress and valgrind all clean.  The five new
assertions were checked by breaking the change five ways: dropping
mssymbol.src from SOURCES, letting issymbol keep a formatting character,
letting a jamo reading keep Hanja, widening isjamo to the vowels, and
making mkhanja reject jamo readings.  Each fails only the tests that exist
for it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

map/README

@@ -1,42 +1,53 @@
 # Dictionary data
 
-## Korean Hanja data
+## Korean Hanja and symbol data
 
-`hanja.src` is the tracked, reviewable source for Korean Hanja conversion.
-Every data row is Hanja, a tab, and its modern Hangul reading, a character
-or a word:
+`hanja.src` and `mssymbol.src` are the tracked, reviewable sources for what
+the Hanja search converts.  Every data row is a result, a tab, and its
+Hangul reading.  A Hanja reads as a syllable or a word; a symbol reads as
+the lone consonant a Korean keyboard's 한자 key offers it under:
 
 ```
 漢	한
 漢字	한자
+※	ㅁ
 ```
 
-`mkhanja` validates that contract and groups rows by their reading to
-produce the runtime dictionary.  Candidate order follows source order.  The
-source keeps all retained pairs for review; the generated dictionary stores
-the first 128 candidates per reading because that is the engine's lookup
-limit.
+`mkhanja` validates that contract and groups the rows of both sources by
+their reading to produce the runtime dictionary.  The two keyspaces do not
+meet: a reading is either syllables or one jamo.  Candidate order follows
+source order.  The sources keep all retained pairs for review; the
+generated dictionary stores the first 128 candidates per reading because
+that is the engine's lookup limit.
 
-The source is derived from libhangul release tag `libhangul-0.2.0`.  The
+The sources are derived from libhangul release tag `libhangul-0.2.0`.  The
 annotated tag object is `20afc38922e3595ee3ed5b186f2ea05afe663763`, its
 peeled commit is `41c702f5d3581325b646ef6249f1f641b0427ae0`, and
-`data/hanja/hanja.txt` has blob ID
-`199cfd70c4b306257ac2e018714a1285f7cf0ed3`.  Import and regenerate it from
-the repository root with:
+`data/hanja/hanja.txt` and `data/hanja/mssymbol.txt` have blob IDs
+`199cfd70c4b306257ac2e018714a1285f7cf0ed3` and
+`31c4e63d74293b6a759d4a2005cd1e7333746631`.  Import and regenerate them
+from the repository root with:
 
 ```sh
 curl -L https://raw.githubusercontent.com/libhangul/libhangul/41c702f5d3581325b646ef6249f1f641b0427ae0/data/hanja/hanja.txt -o upstream
 printf '%s  %s\n' dd44dcc856cf542b1022d0f39c2e9b9f8805fdcc5923be80f04849ed97ce0996 upstream | sha256sum -c -
 map/libhangul2hanja upstream >map/hanja.src
+curl -L https://raw.githubusercontent.com/libhangul/libhangul/41c702f5d3581325b646ef6249f1f641b0427ae0/data/hanja/mssymbol.txt -o upstream
+printf '%s  %s\n' b685a4ebe2716b25eb29c42f6da6493716ecd78b604b44a33420987d21948e99 upstream | sha256sum -c -
+map/libhangul2hanja upstream >map/mssymbol.src
 map/mkhanja >map/hanja.dict
 ```
 
-`libhangul2hanja` retains only rows whose reading is modern Hangul syllables
-throughout and whose value is Hanja the popup can draw: U+3400–U+4DBF,
-U+4E00–U+9FFF, or U+F900–U+FAFF.  Thus jamo readings, mixed values, and
-supplementary-plane ideographs are omitted.  The import preserves the upstream license header and row order.
-The retained data is BSD 3-Clause licensed by Choe Hwanjin; the complete text
-is in `LICENSES/BSD-3-Clause-libhangul-hanja.txt`.
+`libhangul2hanja` keeps a syllable reading only when its value is Hanja the
+popup can draw: U+3400–U+4DBF, U+4E00–U+9FFF, or U+F900–U+FAFF.  Thus mixed
+values and supplementary-plane ideographs are omitted.  It keeps a jamo
+reading, U+3131–U+314E, only when its value is one rune the popup can draw
+and a candidate row can carry — so `mssymbol.txt`'s ideographic space and
+soft hyphen are omitted, leaving 985 of its 987 rows, and a Hanja under a
+jamo reading is omitted as noise.  The import preserves each upstream
+license header and row order.  The retained data is BSD 3-Clause licensed
+by Choe Hwanjin; the complete text is in
+`LICENSES/BSD-3-Clause-libhangul-hanja.txt`.
 
 ## Emoji and symbol data