Add paperless-ngx integration for document storage and share links

- dlib/integrations/paperless.py: sync HTTP client wrapping the paperless-ngx
  REST API (upload doc, poll task, create/delete share links, delete document)
- config: PAPERLESS_ENABLED, PAPERLESS_BASE_URL, PAPERLESS_TOKEN, PAPERLESS_TAG_IDS
- PublicAsset model: paperless_document_id + paperless_share_slug columns
- publication service: after creating the asset, if paperless is enabled upload
  the patched PDF and create a share link; stores doc id + share slug on the asset
- public routes: pass expires_at through to publish_version; new
  POST /{slug}/share-links endpoint to (re)create expiring share links on demand
- schemas: PublishRequest.expires_at, PublicAssetResponse.paperless_share_url,
  new ShareLinkRequest model
- frontend: paperless_share_url field on PublicAsset type, createShareLink()
  and expiresAt param on publishVersion() in api.ts
- .env.example: documented paperless env vars

https://claude.ai/code/session_01YPVs6uBwCvcwVMvrfLBBdu

apps/backend/fastapi/app/services/publication.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import asyncio
 import re
 from datetime import datetime
 from uuid import uuid4
@@ -7,7 +8,11 @@ from uuid import uuid4
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.core.config import get_settings
 from app.models import CvDocument, CvVersion, PublicAsset, Submission
+from app.services.storage import storage_client
+from dlib.cv import docx_bytes_to_pdf, generate_patched_docx
+from dlib.integrations.paperless import get_paperless_client
 
 
 async def publish_version(
@@ -17,6 +22,7 @@ async def publish_version(
     version_id: str | None,
     submission_id: str | None,
     slug: str | None,
+    expires_at: datetime | None = None,
 ) -> PublicAsset | None:
     target_version: CvVersion | None = None
     target_submission: Submission | None = None
@@ -55,11 +61,27 @@ async def publish_version(
         slug=resolved_slug,
         artifact_key=target_version.artifact_docx_key,
         is_public=True,
-        expires_at=None,
+        expires_at=expires_at,
     )
     session.add(asset)
     await session.commit()
     await session.refresh(asset)
+
+    settings = get_settings()
+    client = get_paperless_client(settings)
+    if client:
+        docx = storage_client.download_bytes(target_version.artifact_docx_key)
+        blocks = target_version.structured_blocks or []
+        pdf = docx_bytes_to_pdf(generate_patched_docx(docx, blocks))
+        doc_id = await asyncio.to_thread(
+            client.upload_document, pdf, resolved_slug, settings.paperless_tag_ids or []
+        )
+        _, share_url = await asyncio.to_thread(client.create_share_link, doc_id, expires_at)
+        asset.paperless_document_id = doc_id
+        asset.paperless_share_slug = share_url.split("/share/")[-1]
+        await session.commit()
+        await session.refresh(asset)
+
     return asset