feat(observability): backfill logging for upload, auth, and domain services

Why:
- resolve_auth_context() runs on every authenticated request and logged
  nothing; four distinct rejection reasons (malformed/unknown/inactive/
  expired key, inactive tenant) were all invisible.
- The domain-allowlist rejection in upload_source_file() happens before any
  ingestion_jobs row exists, so it wasn't covered by the job-level
  ingestion.job.failed event either -- a rejected upload left zero trace.
- Four of upload_source_file()'s five failure branches (parse_failed,
  chunk_limit_exceeded, embedding_failed, index_failed) called
  _mark_job_failed(), which wrote to Postgres but never logged; only
  storage_failed and timeout had an ad-hoc logger.warning duplicated at their
  own call sites.

Changes:
- auth/service.py: auth.succeeded / auth.failed (with a reason field per
  rejection type), matching ADR-0011's own event catalog.
- domains/service.py: domain.rejected on the allowlist check;
  domain.created / domain.updated / domain.status_changed on the three
  mutations.
- files/upload.py: centralized failure logging inside _mark_job_failed
  (every failure branch already calls it, so logging there once closes all
  five branches instead of duplicating a log call at each site) as
  ingestion.job.failed; added ingestion.job.started; renamed the ad-hoc
  files.upload.succeeded to ingestion.job.completed for catalog consistency.

Impact:
- None to request/response behavior -- log events only.

tests/integration/postgres/test_auth_service_logging.py

@@ -0,0 +1,134 @@
+"""`resolve_auth_context` emits `auth.succeeded`/`auth.failed` (ADR-0011).
+
+This runs on every authenticated request, so every rejection reason needs a
+distinguishable log event -- previously none of them logged anything.
+"""
+
+from collections.abc import MutableMapping
+from typing import Any
+
+import pytest
+import structlog
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
+
+from src.application.auth.errors import InvalidApiKeyError, TenantInactiveError
+from src.application.auth.service import resolve_auth_context
+from tests.support.factories import create_api_key, create_tenant
+
+pytestmark = [
+    pytest.mark.integration,
+    pytest.mark.postgres,
+    pytest.mark.asyncio(loop_scope="session"),
+]
+
+
+def _events_by_name(
+    logs: list[MutableMapping[str, Any]], name: str
+) -> list[MutableMapping[str, Any]]:
+    return [entry for entry in logs if entry.get("event") == name]
+
+
+async def test_valid_key_emits_auth_succeeded(
+    db_session: AsyncSession, db_sessionmaker: async_sessionmaker[AsyncSession]
+) -> None:
+    tenant = await create_tenant(db_session)
+    _, full_key = await create_api_key(db_session, tenant=tenant, scopes=["files:write"])
+    await db_session.commit()
+
+    with structlog.testing.capture_logs() as logs:
+        auth = await resolve_auth_context(db_sessionmaker, full_key)
+
+    succeeded = _events_by_name(logs, "auth.succeeded")
+    assert len(succeeded) == 1
+    assert succeeded[0]["tenant_id"] == str(auth.tenant_id)
+    assert succeeded[0]["api_key_id"] == str(auth.api_key_id)
+    assert _events_by_name(logs, "auth.failed") == []
+
+
+async def test_malformed_token_emits_auth_failed(
+    db_sessionmaker: async_sessionmaker[AsyncSession],
+) -> None:
+    with structlog.testing.capture_logs() as logs, pytest.raises(InvalidApiKeyError):
+        await resolve_auth_context(db_sessionmaker, "not-a-bearer-token-at-all")
+
+    failed = _events_by_name(logs, "auth.failed")
+    assert len(failed) == 1
+    assert failed[0]["reason"] == "malformed_key"
+
+
+async def test_wrong_secret_emits_auth_failed(
+    db_session: AsyncSession, db_sessionmaker: async_sessionmaker[AsyncSession]
+) -> None:
+    tenant = await create_tenant(db_session)
+    api_key, _ = await create_api_key(db_session, tenant=tenant)
+    await db_session.commit()
+
+    with structlog.testing.capture_logs() as logs, pytest.raises(InvalidApiKeyError):
+        await resolve_auth_context(db_sessionmaker, f"sk_{api_key.key_prefix}_wrong-secret")
+
+    failed = _events_by_name(logs, "auth.failed")
+    assert len(failed) == 1
+    assert failed[0]["reason"] == "unknown_key"
+
+
+async def test_unknown_prefix_emits_auth_failed(
+    db_sessionmaker: async_sessionmaker[AsyncSession],
+) -> None:
+    with structlog.testing.capture_logs() as logs, pytest.raises(InvalidApiKeyError):
+        await resolve_auth_context(db_sessionmaker, "sk_doesnotexist_secret")
+
+    failed = _events_by_name(logs, "auth.failed")
+    assert len(failed) == 1
+    assert failed[0]["reason"] == "unknown_key"
+
+
+async def test_revoked_key_emits_auth_failed_with_key_status(
+    db_session: AsyncSession, db_sessionmaker: async_sessionmaker[AsyncSession]
+) -> None:
+    tenant = await create_tenant(db_session)
+    _, full_key = await create_api_key(db_session, tenant=tenant, status="revoked")
+    await db_session.commit()
+
+    with structlog.testing.capture_logs() as logs, pytest.raises(InvalidApiKeyError):
+        await resolve_auth_context(db_sessionmaker, full_key)
+
+    failed = _events_by_name(logs, "auth.failed")
+    assert len(failed) == 1
+    assert failed[0]["reason"] == "key_inactive"
+    assert failed[0]["key_status"] == "revoked"
+
+
+async def test_suspended_tenant_emits_auth_failed(
+    db_session: AsyncSession, db_sessionmaker: async_sessionmaker[AsyncSession]
+) -> None:
+    tenant = await create_tenant(db_session, status="suspended")
+    _, full_key = await create_api_key(db_session, tenant=tenant)
+    await db_session.commit()
+
+    with structlog.testing.capture_logs() as logs, pytest.raises(TenantInactiveError):
+        await resolve_auth_context(db_sessionmaker, full_key)
+
+    failed = _events_by_name(logs, "auth.failed")
+    assert len(failed) == 1
+    assert failed[0]["reason"] == "tenant_inactive"
+    assert failed[0]["tenant_id"] == str(tenant.id)
+
+
+async def test_auth_failed_never_logs_the_secret(
+    db_session: AsyncSession, db_sessionmaker: async_sessionmaker[AsyncSession]
+) -> None:
+    """ADR-0011's redaction rule: never log plaintext API keys. `key_prefix`
+    is the non-secret lookup portion (same distinction `ApiKey.key_prefix`
+    makes); the secret itself must not appear in any field's value.
+    """
+    tenant = await create_tenant(db_session)
+    api_key, _ = await create_api_key(db_session, tenant=tenant)
+    await db_session.commit()
+    wrong_secret = "definitely-not-the-real-secret"
+
+    with structlog.testing.capture_logs() as logs, pytest.raises(InvalidApiKeyError):
+        await resolve_auth_context(db_sessionmaker, f"sk_{api_key.key_prefix}_{wrong_secret}")
+
+    failed = _events_by_name(logs, "auth.failed")
+    assert len(failed) == 1
+    assert wrong_secret not in str(failed[0])