feat: add host-provided module object storage

`manifest.storage.buckets` has existed since manifest version 1 and meant
nothing — discovery validated it and no code read it. This turns it into a
real capability, which is what stands between Announcements and the module
system: that product currently fetches a hardcoded LAN S3 endpoint, parses
ListObjectsV2 XML by hand, and hands the browser direct object URLs.

- A module declares a logical bucket and receives a scoped facade at
  `context.storage` — list, head, get, put, delete. The contract names no
  provider: no endpoint, region, credential, or physical bucket is reachable
  from it, which is what lets the same module run under a future standalone
  host over its own or a shared S3-compatible service.
- Core's first provider speaks S3 through the AWS SDK. SeaweedFS is the
  deployment target (ADR 0004), never an API name. Probing the pinned image
  found `CreateBucket` reporting `BucketAlreadyExists` rather than AWS's
  `BucketAlreadyOwnedByYou`; treating only the AWS spelling as success would
  have failed every second boot. A live test pins it.
- Logical → physical mapping is deterministic and collision-safe: an
  installation prefix, the module and bucket ids joined by `--` (which cannot
  occur inside either identifier, so `a-b`+`c` and `a`+`b-c` cannot collide),
  and a digest over the full untruncated identity. Two modules declaring
  `assets` always get separate namespaces; neither can see the physical name.
- Declaring a bucket is now a requirement: with no provider configured the
  module is `blocked · storage_unavailable` through ADR 0028's existing
  resolver, propagating to required dependents. An installation with no object
  storage stays a complete deployment.
- Binding availability is not provider health. Eligibility asks whether
  storage is configured, never whether it answered; bucket creation is lazy on
  first use so a storage outage cannot stop the platform booting; a running
  module whose store blinks stays running and retries. Nothing deletes a
  bucket.
- Credentials are deployment-supplied, never persisted, never routed through
  module configuration, and never visible to modules, module UI, diagnostics,
  or API responses. Provider errors translate to a closed code set carrying no
  endpoint, bucket, request id, or XML.
- Retires ADR 0029's transitional `bucket` configuration key. No manifest
  version change. The template declares no bucket, so it still runs without S3.

See ADR 0030.

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

packages/contracts/src/module-http.ts

@@ -2,6 +2,7 @@ import { z } from "zod";
 import type { EkklesiaPrincipal } from "./identity.js";
 import { type ModuleId, type PermissionId, permissionIdSchema } from "./identifiers.js";
 import type { ModuleConfiguration } from "./module-configuration.js";
+import type { ModuleStorage } from "./module-storage.js";
 import type { ModuleRuntimeServices } from "./module-database.js";
 
 // Not imported from `./module-runtime.js`'s own `Awaitable` (structurally identical) — importing
@@ -220,6 +221,10 @@ export interface ModuleRouteHandlerContext {
   readonly moduleId: ModuleId;
   readonly principal: EkklesiaPrincipal;
   readonly params: Readonly<Record<string, string>>;
+  /** The identical scoped storage facade this module's `start`/`stop` hooks received — the same
+   * object, not a re-resolved one (ADR 0030). This is what lets a module stream an object straight
+   * into a `Response` without the browser ever learning that object storage exists. */
+  readonly storage: ModuleStorage;
   readonly services: ModuleRuntimeServices;
   /** The identical frozen configuration snapshot this module's `start`/`stop` hooks received — the
    * same object, not a re-read — so a handler and a lifecycle hook can never disagree about a value