feat: mount discovered module UI in a minimal Ekklesia browser host

Phase 6C pass 2. Every link in the module UI chain existed except the one
that closes it: a module could be authored, built, validated, published at a
browser URL, and loaded by a generic loader — and nothing in Ekklesia did any
of it. There was no browser application at all.

Two pieces were missing. A browser could not discover what to mount, and it
must not work that out for itself.

GET /api/v1/module-ui is the inventory: per publishable module, its id and
version, the server-produced artifact URL, the server-produced root of the
module's own API, and the subset of that module's declared permissions the
caller holds. Five fields, each because building a ModuleUiHostContext needs
it — no filesystem paths, and no name/icon/folder/order, because navigation
metadata is a design that does not exist yet. Its module set is the ADR 0025
publication registry rather than a rescan, so the inventory and the artifact
route cannot disagree. It requires a new Core permission, core.modules.ui.read
(baseline authenticated), because it is precisely the enumeration the anonymous
artifact route deliberately withholds.

Both URLs are server-produced. moduleUiArtifactUrl already existed;
moduleApiBaseUrl is now exported and moduleRoutePath builds on it, so each URL
shape has exactly one author. Without it the shell would hardcode
/api/v1/modules/<id> — the prefix ADR 0022 forbids a module UI from spelling,
reappearing in the host instead.

surfaces/shell (@ekklesia/shell) is the repository's first surface: a small
React application built to static files by its own esbuild script. It resolves
the principal, fetches the inventory, builds the host context entirely from
server-derived data, and hands the artifact URL to @ekklesia/module-ui-host.
One frame per selection — keyed by module identity — defeats the stale-load
race; the host owns the container, the loading state, and every failure, so a
broken module costs its own panel rather than the shell.

The shell statically imports no module, and both levels are checked: no source
import may name a module, and the emitted bundle must contain exactly one
dynamic import (the loader's) with no module id, no /api/v1/modules, no eval,
and no blob URL. Permission hints come from Core's own evaluator and stay
presentation-only — the end-to-end test has a UI holding no grant call its API
anyway and still receive 403.

Surfaces may now depend only on browser-safe shared roles; @ekklesia/contracts
is deliberately excluded, since its barrel pulls Drizzle's types and Node's
globals into the browser — the hole ADR 0024 closed one layer down.

Not the Dashboard: no navigation, grouping, icons, ordering, design system, or
routing. The selector is a list of module ids.

Co-Authored-By: Claude Opus 5 <[email protected]>

README.md

@@ -326,11 +326,39 @@ download that bundle. Caching is `no-cache` with a strong `ETag` rather than `im
 without an installer nothing stops a version being rebuilt with different bytes. See
 [ADR 0025](docs/architecture/decisions/0025-trusted-module-ui-asset-publication.md).
 
-**This is not Dashboard integration.** A host *could* now obtain a browser URL, which was previously
-impossible — but nothing in Ekklesia mounts a module UI. There is no Dashboard shell, no navigation,
-no place a module's screen appears, and no code calls the URL helper outside its own tests. A design
-system, a stylesheet or general asset publication contract, a module metadata endpoint, and the
-standalone host also do not exist.
+Phase 6C pass 2 connects the chain: **Ekklesia now has a browser host that mounts module-owned UI.**
+`surfaces/shell` (`@ekklesia/shell`) is the repository's first surface — a small React application,
+built to static files with esbuild — and it does the whole loop at run time:
+
+```text
+GET /api/v1/principal   →  who is viewing
+GET /api/v1/module-ui   →  which module UIs may be mounted, and where
+        ↓  server-produced artifact URL
+@ekklesia/module-ui-host  →  dynamic import, identity check, mount into a host-owned container
+        ↓
+context.api.request("records")  →  /api/v1/modules/example/records
+```
+
+The new inventory endpoint returns exactly what building a `ModuleUiHostContext` needs — id, version,
+artifact URL, module API root, and the viewer's granted permissions **for that module** — and nothing
+else: no filesystem paths, and no `name`/`icon`/`folder`/`order`, because navigation metadata is a
+design that does not exist yet. It is authenticated (`core.modules.ui.read`, baseline
+`authenticated`) precisely because it is the module enumeration the anonymous artifact route
+deliberately withholds. Both URLs are produced by the server's own canonical helpers, so the browser
+never rebuilds Ekklesia's module prefixes and either can change without touching host or module code.
+
+**The shell statically imports no module.** Every module it can mount arrives at run time from the
+inventory, and its bundle is checked for exactly one dynamic import — the generic loader's — with no
+module id, no `/api/v1/modules`, no `eval`, and no blob URLs. Permission hints come from the server's
+own evaluator and remain presentation only: the end-to-end test proves a viewer holding no grant is
+still refused `403` when the UI calls the API anyway. The host owns the container, the loading state,
+and every failure; a broken module costs its own panel, not the shell. See
+[ADR 0026](docs/architecture/decisions/0026-minimal-ekklesia-module-ui-host.md).
+
+**This is not the Dashboard.** There is no navigation model, grouping, folders, icons, ordering, home
+screen, design system, or client-side routing — the selector is a list of module ids. Sign-in UI, a
+production CSP and deployment for the built shell, asset publication beyond the UI entrypoint, React
+runtime sharing, the standalone host, and every real feature module also do not exist.
 
 **Security model.** Installed modules are trusted compiled backend code that runs arbitrary
 JavaScript in the API process and shares its PostgreSQL role — table prefixes, manifests, permission