Issues 173 and 174 resolved; the installation check refuses at registration (ADR 0155)

A setting overrides a key a contribution or served fact declares and adds none; a provider that must
tell its consumers an operator's value declares it as ${setting:…} (173). The mesh's own files for a
module are a placed directory, `place: "mesh"`, and forty-eight definitions name no host path for
them (174). Registration refuses a definition naming an installation, the day the list emptied
rather than a release later (0155, progressive insight; 134). Designs 27 and 18 carry the rules.

03-DESIGN/01-to-be/18-building-a-module.md

@@ -234,7 +234,7 @@ counts as a copy and what as a base.
 
 | resource | is | a module may |
 |---|---|---|
-| `directory` | a directory with a mode and an owner | ✅ |
+| `directory` | a directory with a mode and an owner, **placed by the mesh** under the node's root: `place: "."` is the assignment's own root, `place: "mesh"` the mesh's directory for the module, a pathless one sits beneath the root by its id; a stated path is the placement for data that must stay where it is, and may itself sit beneath a placed one (`${dir:<id>}/…`). Everything else names it as `${dir:<id>}` ([issue 119](../../04-ISSUES/119-a-module-definition-decides-where-its-files-live/00-report.md), [174](../../04-ISSUES/174-the-meshs-own-files-for-a-module-are-placed-by-the-definition/00-report.md)) | ✅ |
 | `file` | literal content, with `${bound:…}`, `${secret:…}`, `${dir:…}`, `${port:…}`, `${machine:…}` and `${setting:…}` filled in — the last an operator's value from the assignment's settings, refused by name when unset ([ADR 0155](../../02-DECISIONS/0155-a-definition-names-no-installation-and-how-that-is-checked.md)) | ✅ |
 | `user` | a login | ✅ |
 | `access` | a pre-existing path it may use and must not own | ✅ |