ja: read the remaining fractions denominator-first, and name the menclose marks

[yasumorishima]

Two groups of fixes in the shared ja rule files. Everything stays inside Rules/Languages/ja/ and tests/Languages/ja/.

1. Three fraction rules read the fraction backwards

Japanese states the denominator first: 3/4 is "4 分の 3". Numerator-first does not just sound odd, it names a different number — "3 分の 4" is 4/3.

common-fraction in ClearSpeak_Rules.yaml and SimpleSpeak_Rules.yaml already swaps the operands, but three rules were still numerator-first:

• SharedRules/default.yaml literal-simple (tag mfrac, reached with SpeechStyle=LiteralSpeak, which is also what navigation falls back to in Character mode — src/navigate.rs:588)
• overview.yaml overview-default (what DescribePrevious/Next/Current speak)

Both now say the denominator first, with the same comment common-fraction carries.

• SharedRules/default.yaml literal-default has explicit start/end markers, so instead of swapping it keeps the written order and uses the borrowed オーバー — the form Yamaguchi, Kawane & Sawazaki (1996) give for a fraction that is not two plain numbers: 分数 A オーバー B 分数終了. It also opened with スタート, the English word "start".

Note on scope: literal-simple matches any two leaves, so it now says 分の for x/y as well as for 3/4. The cited source reserves 分の for two numbers, but "b 分の a" is ordinary Japanese for a fraction of two symbols too, and this rule has no start/end markers to hang the オーバー form on.

2. Names that were still the machine translation

SharedRules/default.yaml, menclose:

notation	was	now	why
uparrow	上下矢印	上矢印	上下矢印 is an arrow with a head at each end
downarrow	ダウン矢印	下矢印	half English
updownarrow	ダブルエンド垂直矢印	上下矢印	the name unicode-full.yaml:558 already gives ↕
leftrightarrow	ダブルエンド水平矢印	左右矢印	the name unicode-full.yaml:557 already gives ↔
northeastsouthwestarrow	ダブルは対角矢印を終了	北東・南西矢印	"double is ends diagonal arrow" is not a sentence; the name is unicode-full.yaml:1824 for ⤢
northwestsoutheastarrow	二重は対角矢印を終了	北西・南東矢印	same, unicode-full.yaml:1823 for ⤡
updiagonalstrike	対角形	右上がり方向	"diagonal shape" does not say which diagonal; 方向 matches the 垂直方向 / 水平方向 beside it
downdiagonalstrike	ダウンの対角	右下がり方向	half English
crossout	クロスアウト	取り消し線
box / roundedbox / circle	ボックス / ラウンドボックス / サークル	四角 / 角丸の四角 / 円
empty box	空の箱	空の四角	so that "box" is one word in this file
actuarial	行動シンボル	保険数理記号	行動シンボル is an "action symbol"
madrub	アラビア語の要素のシンボル	アラビア文字の階乗記号	reads "Arabic-language element symbol"; madrub is the factorial symbol written in Arabic script
longdiv	ロングディビジョンシンボル	割り算の筆算の記号

Also in SharedRules/default.yaml, the mover and munderover rules said 詳しくはこちら for "above". That is the web phrase "click here for details"; the word wanted is 上, the partner of the 下 already in the rule beside it.

And three single words:

• SharedRules/linear-algebra.yaml — ノルダム is Notre-Dame. A norm is ノルム.
• SharedRules/general.yaml 1x1-matrix — エントリー → 成分, the term for a matrix entry.
• SharedRules/general.yaml default-point and unicode.yaml . — ポイント → 点, which is what geometry.yaml:71 already says for a coordinate and what a Japanese reader says for a decimal point.

Checks

• audit-translations ja: Untranslated text 3493 → 3462. That is exactly −31, the number of lines promoted from t: to T: after checking each against the en line beside it. Missing rules 0, extra rules 0, and Rule differences 28 → 28, i.e. swapping the two operands did not make the rules diverge structurally from en.
• 10 tests added: both fraction paths, the overview path, the menclose strikes / shapes / long division / arrows, above and below, the norm, the matrix entry and the coordinate. Every expected string is the actual output.
• The . character rule in unicode.yaml is the one change with no test: I could not build MathML that reaches its parent::*[1][self::m:mn] branch — a plain <mn>3.5</mn> is spoken as one token.
• The 分の lines in ClearSpeak_Rules.yaml and SimpleSpeak_Rules.yaml are promoted to T: as well, so the word is not verified in two files and unverified in two others.

Left alone on purpose

• unicode-full.yaml, waiting for the MathPlayer seed.
• navigate.yaml, which Translate the Japanese navigation command prefixes #752 is already touching. I checked that the two branches merge cleanly in either order and give the same tree.
• phasorangle (フェーザの角度) and the single compass arrows (北東矢印 etc.) are literal but not wrong, so I left them.
• The relation symbols in unicode.yaml are inconsistent — < is 小なり but > is より大きい, and ∈ is 要素の where the source gives 要素オブ. That is a separate theme and will be a separate PR.