docs: add external documentation site content

Add structured documentation covering quickstart, architecture, core
concepts, API reference, adapter guides, CLI commands, deployment
options, and operator/developer guides.

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

docs/deploy/storage.md

@@ -0,0 +1,41 @@
+---
+title: Storage
+summary: Local disk vs S3-compatible storage
+---
+
+# Storage
+
+Paperclip stores uploaded files (issue attachments, images) using a configurable storage provider.
+
+## Local Disk (Default)
+
+Files are stored at:
+
+```
+~/.paperclip/instances/default/data/storage
+```
+
+No configuration required. Suitable for local development and single-machine deployments.
+
+## S3-Compatible Storage
+
+For production or multi-node deployments, use S3-compatible object storage (AWS S3, MinIO, Cloudflare R2, etc.).
+
+Configure via CLI:
+
+```sh
+pnpm paperclip configure --section storage
+```
+
+## Configuration
+
+| Provider | Best For |
+|----------|----------|
+| `local_disk` | Local development, single-machine deployments |
+| `s3` | Production, multi-node, cloud deployments |
+
+Storage configuration is stored in the instance config file:
+
+```
+~/.paperclip/instances/default/config.json
+```