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>

server/package.json

@@ -16,10 +16,12 @@
     "@paperclip/adapter-utils": "workspace:*",
     "@paperclip/db": "workspace:*",
     "@paperclip/shared": "workspace:*",
+    "@aws-sdk/client-s3": "^3.888.0",
     "detect-port": "^2.1.0",
     "dotenv": "^17.0.1",
     "drizzle-orm": "^0.38.4",
     "express": "^5.1.0",
+    "multer": "^2.0.2",
     "pino": "^9.6.0",
     "pino-http": "^10.4.0",
     "pino-pretty": "^13.1.3",
@@ -32,6 +34,7 @@
   "devDependencies": {
     "@types/express": "^5.0.0",
     "@types/express-serve-static-core": "^5.0.0",
+    "@types/multer": "^2.0.0",
     "@types/supertest": "^6.0.2",
     "supertest": "^7.0.0",
     "tsx": "^4.19.2",