feat: build Signage on its own from the published Ekklesia 0.2.0 packages

Signage no longer needs an Ekklesia checkout. A clean clone installs with
`pnpm install --frozen-lockfile` and runs lint, typecheck, test, build, and validate by itself, taking
Ekklesia's module-development packages from Ekklesia's public registry (ADRs 0053 and 0054).

- Dependencies: every `workspace:*` becomes `^0.2.0`. @ekklesia/module-pack is added as a
  devDependency pinned exactly to 0.2.0, as ADR 0053 requires; it is not invoked yet. No
  @ekklesia/contracts dependency. drizzle-orm stays a direct dependency, satisfying the adapter's
  optional peer.
- .npmrc points the @ekklesia scope at
  https://git.riverofglorymn.org/api/packages/River_of_Glory_Church/npm/ with no credential, because
  reading needs none.
- pnpm-workspace.yaml holds this repository's pnpm settings only:
  - `allowBuilds: esbuild: true`, as the platform's standalone fixture does;
  - exact-version minimumReleaseAgeExclude entries for the 0.2.0 train, which pnpm 11 otherwise holds
    back on its release day;
  - the platform's narrowly scoped override for GHSA-67mh-4wv8-2f99 (esbuild via drizzle-kit), which
    Signage inherited while it built inside Ekklesia's workspace.
- engines.node `>=24.11.0 <25` and packageManager `[email protected].0`, both from Ekklesia 0.2.0. Node
  24.18.0 goes in .node-version for CI, as in Ekklesia.
- biome.json carries the platform's Biome configuration, which `biome lint` used to pick up from the
  workspace root, so lint rules are unchanged.
- pnpm-lock.yaml is Signage's own: registry tarballs with integrity hashes, and no workspace or file
  links.
- `prepack` runs this package's own build instead of the workspace root's turbo.
- `pnpm validate` (scripts/validate-module.mjs) checks the built package and its migrations with the
  published SDK parsers only:
  - the manifest, its identity, and its entrypoints;
  - that the built runtime's id, version, and database ABI match the manifest;
  - that the built schema metadata is plain, namespaced, and has module-internal foreign keys;
  - the SDK compatibility range;
  - that the migration journal and policy agree.

  Core's own `modules:validate` and `migrations:validate` are not published. What only an Ekklesia
  installation can check is named in the script.

Removed: ci/assemble.sh, ci/platform.env, ci/pnpm-lock.yaml, ci/update-lock.sh. The lint, typecheck,
test, and build jobs check out only this repository; build also runs `pnpm validate`. The integration
job stays disabled. Its first step is now an explicit placeholder rather than the deleted assembly,
and its explanation says it returns when Signage is a canonical linux-x64-glibc Module Package
installed into Ekklesia's generic image.

No source, behaviour, schema, or version change: Signage stays 0.1.2.

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

.npmrc

@@ -0,0 +1,3 @@
+# Ekklesia's module-development packages (@ekklesia/*) come from Ekklesia's public package registry
+# (platform ADRs 0053 and 0054). Reading needs no account and no token; never put a credential here.
+@ekklesia:registry=https://git.riverofglorymn.org/api/packages/River_of_Glory_Church/npm/