czech: fill in the lins needed to build an application grammar

The Czech resource was too incomplete to compile a Syntax/Grammar client:
Sentence, Idiom and Question defined almost nothing, and many Structural
words were absent, so MissingCze's notYet stubs were reached at PMCFG
generation time.

Added:
  CatCze        lincat VV
  SentenceCze   AdvS, ExtAdvS, SSubjS, EmbedS, EmbedQS, ImpVP
  IdiomCze      ImpP3, ExistNP, ImpersCl, GenericCl
  VerbCze       CompCN, ComplVS, ComplVV, PassV2
  NounCze       SentCN, PredetNP
  AdverbCze     SubjS
  QuestionCze   QuestIAdv
  PhraseCze     UttImpSg, UttImpPl, UttImpPol
  StructuralCze all_Predet, both7and_DConj, between_Prep, by8means_Prep,
                can_VV, either7or_DConj, every_Det, if_Subj, no_Quant,
                on_Prep, someSg_Det, that_Subj, under_Prep, where_IAdv
  ExtendCze     ExistsNP no longer excluded

Three of these approximate, because VerbForms lacks the required forms:
ImpVP uses the 1st person plural present ("předpokládáme, že ...") as there
is no imperative; PassV2 uses the reflexive passive ("číslo se dělí") as
passpart is commented out in ResCze; ImpP3 uses "nechť", which suits
mathematical text more than the "let John walk" of the RGL example.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/czech/AdverbCze.gf

@@ -6,4 +6,8 @@ lin
       s = prep.s ++ np.prep ! prep.c
       } ;
 
+    SubjS subj s = {
+      s = subj.s ++ s.s
+      } ;
+
 }