docs(storage): record the presigned-download options in the hand-written contract docs

The drift check flagged these: both storage-service pages transcribe
IStorageService by hand, and this PR adds an optional PresignedDownloadOptions
argument to getSignedUrl / getPresignedDownload. Left alone they would describe
a signature the code no longer has — the same declared-vs-actual gap the rest of
this PR is about, one level up in the docs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SHpGw3GBA9aFpfwVArRWfd

Author: claude

.claude/launch.json

@@ -18,6 +18,24 @@
         "file:/tmp/showcase-dogfood-3777/data.db"
       ],
       "port": 3777
+    },
+    {
+      "name": "pr3505-attach-3477",
+      "runtimeExecutable": "pnpm",
+      "runtimeArgs": [
+        "-C",
+        "/home/user/objectstack-pr3505/examples/app-showcase",
+        "exec",
+        "objectstack",
+        "dev",
+        "--ui",
+        "--seed-admin",
+        "-p",
+        "3477",
+        "-d",
+        "file:/tmp/pr3505-attach/data.db"
+      ],
+      "port": 3477
     }
   ]
 }

content/docs/kernel/contracts/storage-service.mdx

@@ -29,15 +29,19 @@ export interface IStorageService {
   list?(prefix: string): Promise<StorageFileInfo[]>;
 
   // Signed URL (optional)
-  getSignedUrl?(key: string, expiresIn: number): Promise<string>;
+  getSignedUrl?(key: string, expiresIn: number, options?: PresignedDownloadOptions): Promise<string>;
 
   // Presigned browser-direct upload / download (optional)
   getPresignedUpload?(
     key: string,
     expiresIn: number,
     options?: StorageUploadOptions,
   ): Promise<PresignedUploadDescriptor>;
-  getPresignedDownload?(key: string, expiresIn: number): Promise<PresignedDownloadDescriptor>;
+  getPresignedDownload?(
+    key: string,
+    expiresIn: number,
+    options?: PresignedDownloadOptions,
+  ): Promise<PresignedDownloadDescriptor>;
 
   // Chunked / multipart upload (optional)
   initiateChunkedUpload?(key: string, options?: StorageUploadOptions): Promise<string>;

content/docs/kernel/runtime-services/storage-service.mdx

@@ -17,14 +17,14 @@ services.storage.delete(key: string): Promise<void>
 services.storage.exists(key: string): Promise<boolean>
 services.storage.getInfo(key: string): Promise<StorageFileInfo>
 services.storage.list?(prefix: string): Promise<StorageFileInfo[]>
-services.storage.getSignedUrl?(key: string, expiresIn: number): Promise<string>
+services.storage.getSignedUrl?(key: string, expiresIn: number, options?: PresignedDownloadOptions): Promise<string>
 ```
 
 ## Presigned / Chunked (optional)
 
 ```ts
 services.storage.getPresignedUpload?(key: string, expiresIn: number, options?: StorageUploadOptions): Promise<PresignedUploadDescriptor>
-services.storage.getPresignedDownload?(key: string, expiresIn: number): Promise<PresignedDownloadDescriptor>
+services.storage.getPresignedDownload?(key: string, expiresIn: number, options?: PresignedDownloadOptions): Promise<PresignedDownloadDescriptor>
 services.storage.initiateChunkedUpload?(key: string, options?: StorageUploadOptions): Promise<string>
 services.storage.uploadChunk?(uploadId: string, partNumber: number, data: Buffer): Promise<string>
 services.storage.completeChunkedUpload?(uploadId: string, parts: Array<{ partNumber: number; eTag: string }>): Promise<string>