Add Quenya ⟨ht⟩ digraph

According to Appendix E of The Lord of the Rings, “[t]he Quenya
combination ht has the sound of cht, as in German echt, acht”. As echt
and acht do not have the same cht sound in German, I assume this means
that they are allophones in Quenya just as in German, and ⟨ht⟩ means
[çt] after front vowels but [xt] after back vowels. Add tests for both:
Telumehtar, the Quenya name of the star Orion, is given in Appendix E as
an example of ⟨ht⟩; Mahtar is the father of Nerdanel, wife of Fëanor.

dictsource/qya_rules

@@ -1,5 +1,9 @@
 // syllable nuclei: vowels (any length) and diphthongs
 .L01 i e a o u í é á ó ú î ê â ô û ui oi ai iu eu au
+// front vowels (finally): after these, ht is [çt]
+.L02 i e í é î ê ui oi ai
+// back vowels (finally): after these, ht is [xt]
+.L03 a o u á ó ú â ô û iu eu au
 
 .replace
 	// turn x into cs, both because that’s how it’s pronounced
@@ -63,7 +67,9 @@
 
 .group h
 	h	h
-	// TODO ht, hl, hr, hw, hy
+	L02) ht	Ct
+	L03) ht	xt
+	// TODO hl, hr, hw, hy
 
 .group i
 	i	i

tests/language-pronunciation.test

@@ -186,7 +186,7 @@ S'a
 'OksidU
 p'or-
 z'&~Ng&U~_:_: ,E*&U~ p,&l'avR&Z dU p,u*@-tug'es#" "Luís argüia à Júlia que «brações, fé, chá, óxido, pôr, zângão» eram palavras do português." "Latn"
-test_phon qya ",aInul'indal,e ald'iNga aNk'alim,a and'u:Ril at'akwe k,alak'iRja k,uivi;'e:nen ,eaR'endil el'endil ,elent'a:Ri; el'essaR 'eNkwi;,e e'onwe eR'esse,a h,elkaR'akse hj'aRmen is'ilduR nam'a:Ri;,e n,u:men'o:Re 'oRom,e ot'okwe pel'o:Ri s'aURon tan'ikwet,il tuR'ambaR und'o:mi;,el ut'umno" "Ainulindalë aldinga ancalima Andúril ataquë Calacirya Cuiviénen Eärendil Elendil Elentári Elessar enquië Eönwe Eressëa Helcaraxë Hyarmen Isildur Namárië Númenórë Orome otoquë Pelóri Sauron Taniquetil Turambar Undómiel Utumno" "Quenya"
+test_phon qya ",aInul'indal,e ald'iNga aNk'alim,a and'u:Ril at'akwe k,alak'iRja k,uivi;'e:nen ,eaR'endil el'endil ,elent'a:Ri; el'essaR 'eNkwi;,e e'onwe eR'esse,a h,elkaR'akse hj'aRmen is'ilduR m'axtan nam'a:Ri;,e n,u:men'o:Re 'oRom,e ot'okwe pel'o:Ri s'aURon tan'ikwet,il t,elum'eCtaR tuR'ambaR und'o:mi;,el ut'umno" "Ainulindalë aldinga ancalima Andúril ataquë Calacirya Cuiviénen Eärendil Elendil Elentári Elessar enquië Eönwe Eressëa Helcaraxë Hyarmen Isildur Mahtan Namárië Númenórë Orome otoquë Pelóri Sauron Taniquetil Telumehtar Turambar Undómiel Utumno" "Quenya"
 test_phon ro "m,uzikol'og@_! yn b'eZ v'ynd wh'iski Si tekw'ila
 p@-*'ets f'iks" "Muzicologă în bej vând whisky și tequila, preț fix." "Latn"
 test_phon ru "Syr'okVja E#l;ikt@-r;if;ik'Atsyja 'juZnyx gub;'ern;ij d'Ast m'oS;nyj tVltS;'ok pVdj'8mu s;'elskVvV xVz;'Ajstva#" "Широкая электрификация южных губерний даст мощный толчок подъёму сельского хозяйства." "Cyrl"