Merge lang/i18nkeys (27024de) into lang/syntax: the vocabulary gains the text keys - the Key type, @TextKey (a registry's), the k"..." and kn"..." literals - and @Text's doc; docs/language pages for Key and @TextKey; ludic-dev syntax rewrote the grammars; reseeded, bootstrap-cfree fixpoint holds

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

changes/text-keys.md

@@ -0,0 +1,16 @@
+bump: minor
+type: feature
+**Text keys: `k"pause.resume"`, a `Key`, checked against `en.po`.** A text the player reads is named by
+a key of the new builtin type `Key` (`kn"..."` for a plural) - not a string, and no string one; at run
+time its text after a marker byte, so a runtime's `tr` is a cast. `lang "assets/lang" en` in
+`package.ludic` names the source language's `.po`, and the compiler holds every key to it: a key
+literal, a template's `t('key', ...)` and a registry's derived `@Text` key (`<registry>.<row>.<field>`,
+or `@TextKey("steps")`'s prefix; filled into a `Key` field a row leaves out) must be there, a plural
+one with a `msgid_plural`; `trf` / `trn` / `t()` given another number of values than the English has
+holes, text still written in English (a template's words, a `@Text` row's value - counted as
+`english_left` by `ludic deps`) and one English split into keys without `#.` descriptions are
+warnings. `ludic schema` gains `"lang"`: every key with its sites, unused and undescribed keys, splits,
+and each other language's missing, fuzzy and extra keys.
+A `Key` in a template literal's hole is an error (write `trf(k"...", ...)`), `trn` takes only a plural
+key and `tr` / `trf` refuse one; a program with no `lang` line (a package test) uses key literals
+unchecked and silently.