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/tests/module-manifest.test.ts

@@ -5,6 +5,7 @@ import {
   MODULE_BLOCKED_REASONS,
   MODULE_CONFIGURATION_BLOCKED_REASONS,
   MODULE_DEPENDENCY_KINDS,
+  MODULE_STORAGE_BLOCKED_REASON,
   MODULE_MANIFEST_VERSION,
   MODULE_RUNTIME_STATES,
   packageRelativePathSchema,
@@ -364,7 +365,13 @@ describe("module manifest contract", () => {
       "configuration_missing",
       "configuration_invalid",
       "secret_missing",
+      "storage_unavailable",
     ]);
+    // Storage adds exactly one reason, and only one: a *binding* that cannot be supplied. A
+    // configured provider that is temporarily unreachable is deliberately not a lifecycle state
+    // (ADR 0030), so there is no `storage_unreachable` here and there must never be.
+    expect(MODULE_BLOCKED_REASONS).not.toContain("storage_unreachable");
+    expect(MODULE_STORAGE_BLOCKED_REASON).toBe("storage_unavailable");
     // The three configuration reasons are a subset, and each corresponds to a real implemented
     // check with a distinct operator fix (ADR 0029) — the only justification for a separate code.
     expect(MODULE_CONFIGURATION_BLOCKED_REASONS).toEqual([