feat: add storage system with local disk and S3 providers

Introduces a provider-agnostic storage subsystem for file attachments.
Includes local disk and S3 backends, asset/attachment DB schemas, issue
attachment CRUD routes with multer upload, CLI configure/doctor/env
integration, and enriched issue ancestors with project/goal resolution.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/shared/src/validators/index.ts

@@ -36,11 +36,13 @@ export {
   checkoutIssueSchema,
   addIssueCommentSchema,
   linkIssueApprovalSchema,
+  createIssueAttachmentMetadataSchema,
   type CreateIssue,
   type UpdateIssue,
   type CheckoutIssue,
   type AddIssueComment,
   type LinkIssueApproval,
+  type CreateIssueAttachmentMetadata,
 } from "./issue.js";
 
 export {

packages/shared/src/validators/issue.ts

@@ -42,3 +42,9 @@ export const linkIssueApprovalSchema = z.object({
 });
 
 export type LinkIssueApproval = z.infer<typeof linkIssueApprovalSchema>;
+
+export const createIssueAttachmentMetadataSchema = z.object({
+  issueCommentId: z.string().uuid().optional().nullable(),
+});
+
+export type CreateIssueAttachmentMetadata = z.infer<typeof createIssueAttachmentMetadataSchema>;