Set up document management for Stirling Engine (#6476)

# Description of Changes
Change Stirling Engine to support deleting documents automatically. This
happens both on user logout and after an amount of time specified by the
Java when ingesting a document (allowing for personal documents to have
short lifetimes but org documents to be left in the db with no expiry
date). Also sets up an [ACL
policy](https://en.wikipedia.org/wiki/Access-control_list) for the
documents so the database knows which users have access to which
documents. This is not fully implemented in the Java, so currently all
docs are treated as having a single owner, the uploader, but
theoretically when we need to support org storage, we shouldn't need to
change the db schema.

engine/tests/contradiction/test_review_integration.py

@@ -8,6 +8,7 @@ contradiction and the right cross-references and anchor handling.
 from __future__ import annotations
 
 import json
+from collections.abc import Iterator
 from dataclasses import replace
 from typing import Literal
 from unittest.mock import AsyncMock
@@ -27,11 +28,25 @@ from stirling.contracts import (
 )
 from stirling.contracts.contradiction import Claim
 from stirling.documents import DocumentService, SqliteVecStore
-from stirling.models import FileId, ToolEndpoint
+from stirling.models import FileId, OwnerId, PrincipalId, ToolEndpoint, UserId
 from stirling.models.tool_models import AddCommentsParams
+from stirling.services import current_user_id
 from stirling.services.runtime import AppRuntime
 from tests.test_pdf_question_agent import StubEmbedder
 
+USER = UserId("test-user")
+OWNER = OwnerId("test-user")
+OWNER_PRINCIPALS = [PrincipalId("test-user")]
+
+
+@pytest.fixture(autouse=True)
+def _set_user_context() -> Iterator[None]:
+    token = current_user_id.set(USER)
+    try:
+        yield
+    finally:
+        current_user_id.reset(token)
+
 
 def _file(file_id: str, name: str) -> AiFile:
     return AiFile(id=FileId(file_id), name=name)
@@ -88,6 +103,9 @@ async def test_localiser_prompt_escapes_verdict_tag_injection(
         file.id,
         [PageText(page_number=1, text="x")],
         source=file.name,
+        owner_id=OWNER,
+        read_principals=OWNER_PRINCIPALS,
+        expires_at=None,
     )
 
     agent = PdfReviewAgent(runtime_with_stub_docs)
@@ -159,6 +177,9 @@ async def test_contradiction_intent_emits_add_comments_plan(
         file.id,
         [PageText(page_number=1, text="ignored"), PageText(page_number=5, text="ignored")],
         source=file.name,
+        owner_id=OWNER,
+        read_principals=OWNER_PRINCIPALS,
+        expires_at=None,
     )
 
     agent = PdfReviewAgent(runtime_with_stub_docs)
@@ -264,6 +285,9 @@ async def test_contradiction_takes_precedence_over_math(
         file.id,
         [PageText(page_number=1, text="x")],
         source=file.name,
+        owner_id=OWNER,
+        read_principals=OWNER_PRINCIPALS,
+        expires_at=None,
     )
 
     agent = PdfReviewAgent(runtime_with_stub_docs)