feat(shell): make module pages first-class top-level routes

Module pages move from `/modules/<id>` to `/<module-id>` (`/signage`),
beside `/settings` and `/account`, so the implementation concept
"module" never appears in a user-facing address. ADR 0057 is rewritten
to match.

- Core reserves the top-level names the platform actually serves today
  (`account`, `api`, `assets`, `display`, `settings`), and discovery
  refuses a module that declares one with `MODULE_ID_RESERVED`. That
  covers startup, `modules:validate`, and package verification. Tests in
  `apps/api` hold the set to every top-level route the API registers and
  every page the shell interprets.
- The API serves the Dashboard page at `/<module-id>` and below only for
  modules discovered with a Dashboard UI, enabled or not: a disabled
  module's bookmark still opens the Dashboard, which says it is
  unavailable. An arbitrary root path such as
  `/definitely-not-a-real-module` stays the sanitized 404.
- Both reference proxies forward every top-level path shaped like a
  module id and let the API decide; the split Dashboard hostname still
  refuses `/api`, `/display`, and `/assets`. Installing a module needs no
  proxy change.
- `/<module-id>/<page>` is already served and forwarded, so a later
  module sub-page contract needs no routing or deployment change; the
  shell shows "Page not found" there until it exists.
- The deploy smoke checks a module's address before install, while
  installed, while disabled, after removal, and after reinstall, plus
  unknown names and the old `/modules/…` form through the real proxy.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

scripts/smoke-deploy.sh

@@ -543,9 +543,13 @@ recreate_api() {
   fi
 }
 
-# module_check <expectation>: "absent", or the exact JSON array of values `example` must return.
+# module_check <expectation> [page]: "absent", or the exact JSON array of values `example` must
+# return. `page` is whether its Dashboard address is served (ADR 0057): by default, exactly when the
+# module is running; "served" for a module that is installed but disabled, whose address still opens
+# the Dashboard so it can say the module is unavailable.
 module_check() {
   client module --ip "$module_client_address" -e SMOKE_MODULE_EXPECT="$1" \
+    -e SMOKE_MODULE_PAGE="${2:-}" \
     -e SMOKE_MODULE_ID="$module_id" -e SMOKE_MODULE_PROBE_PATH="$module_probe_path" \
     -e SMOKE_OWNER_EMAIL="$owner_email" -e SMOKE_OWNER_PASSWORD="$owner_password"
 }
@@ -729,7 +733,7 @@ if [[ "$topology" == split ]]; then
   step "Disabling and re-enabling the module through the supported lifecycle command"
   restart_api "${compose[@]}" run --rm --no-deps migrate node \
     core/dist/cli/set-module-enabled.js --disable --module "$module_id"
-  module_check absent || fail "the disabled module was still reported as running."
+  module_check absent served || fail "the disabled module was still reported as running."
   module_storage "test -d /modules/${module_id}" ||
     fail "disabling the module removed its installed package."
   restart_api "${compose[@]}" run --rm --no-deps migrate node \