Document the two languages, and how to contribute a third

Both manuals get the language picker in full: where it sits, that it applies per profile and
takes effect at once in every open window, and -- at more length -- what is deliberately left
alone and why. An operator who sees an English beacon text in a German client should be able
to read that it is meant that way.

The contribution route is written down in both, because plain text files are only useful if
somebody knows they are there: copy, translate, submit; a partial file is welcome; the build
reports mistakes by file name and writes a worksheet of what is still missing.

PROJECT_CONTEXT records the decisions that outlive this stage -- the four kinds of text and
the rule that the addressee decides, that core produces no display text, that incompleteness
is allowed and incorrectness is not, that anything built outside a composition needs its text
read inside one, and that a column id is never translated.

CLAUDE.md said two modules; there are three, and the third never ships. It also states the
German orthography now, which this session got wrong across a spec and two plans: ss after a
short vowel, so muss and dass.

docs/superpowers/plans/2026-10-04-farben-anpassbar.md

@@ -1269,7 +1269,7 @@ denselben vier Pfaden, nicht `git add -A`.
 > | Text im Feld | 21,0 | **≈2,9** |
 > | Akzent auf Fläche | **2,86** | **2,26** |
 >
-> Eine absolute Grenze würde also ab dem ersten Start in beiden Entwürfen warnen, ohne daß
+> Eine absolute Grenze würde also ab dem ersten Start in beiden Entwürfen warnen, ohne dass
 > der Operateur etwas getan hätte — und eine Warnung, die immer leuchtet, bringt ihm bei,
 > Warnungen zu übersehen. Die Grenze bis zum Durchkommen der Vorlagen zu senken (auf etwa
 > 2,2) macht sie wertlos.