feat(library): register IngestJob admin and link Neo4j views

- Add read-only ModelAdmin for IngestJob with filters, search, and
  date hierarchy for operational visibility
- Inject proxy entries into the admin index for Neo4j-backed entities
  (Libraries, Concepts, Search, Embedding pipeline) that link to
  existing CRUD views in library/views.py
- Makes library content discoverable from /admin/ without pretending
  neomodel StructuredNodes are Django ORM models

mnemosyne/library/admin.py

@@ -1,5 +1,123 @@
-# Library app does not use standard Django admin (neomodel StructuredNodes
-# are not Django ORM models). Custom admin views are provided as regular
-# app views in library/views.py, rendered within Themis's template structure.
-#
-# The embedding pipeline dashboard is at /library/embedding/
+"""Admin registrations for the library app.
+
+Most library content (Library, Collection, Item, Chunk, Concept, Image,
+ImageEmbedding) lives in Neo4j via neomodel and cannot use Django's
+standard ModelAdmin. Those entities have full CRUD pages in
+``library/views.py``; this module wires proxy rows into the admin index
+so they are discoverable from ``/admin/``.
+
+``IngestJob`` is a regular Django ORM model and gets a normal,
+read-only ModelAdmin.
+"""
+
+from django.contrib import admin
+from django.urls import NoReverseMatch, reverse
+
+from .models import IngestJob
+
+
+@admin.register(IngestJob)
+class IngestJobAdmin(admin.ModelAdmin):
+    list_display = (
+        "id",
+        "status",
+        "library_uid",
+        "item_uid",
+        "source",
+        "source_ref",
+        "progress",
+        "retry_count",
+        "created_at",
+        "completed_at",
+    )
+    list_filter = ("status", "source", "created_at")
+    search_fields = (
+        "id",
+        "library_uid",
+        "item_uid",
+        "source_ref",
+        "content_hash",
+        "title",
+        "celery_task_id",
+    )
+    date_hierarchy = "created_at"
+    ordering = ("-created_at",)
+    readonly_fields = (
+        "id",
+        "item_uid",
+        "library_uid",
+        "celery_task_id",
+        "status",
+        "progress",
+        "error",
+        "retry_count",
+        "chunks_created",
+        "concepts_extracted",
+        "embedding_model",
+        "content_hash",
+        "source",
+        "source_ref",
+        "s3_key",
+        "title",
+        "file_type",
+        "file_size",
+        "collection_uid",
+        "created_at",
+        "started_at",
+        "completed_at",
+    )
+
+    def has_add_permission(self, request):
+        return False
+
+    def has_change_permission(self, request, obj=None):
+        # View-only; superusers can still open the detail page.
+        return request.method in ("GET", "HEAD")
+
+
+# ---------------------------------------------------------------------------
+# Neo4j-resident entities: proxy entries on the admin index that link to the
+# existing CRUD views in library/views.py. No shim models — just an honest
+# signpost so /admin/ doesn't pretend the library is empty.
+# ---------------------------------------------------------------------------
+
+_NEO4J_ADMIN_LINKS = [
+    ("Libraries", "library:library-list"),
+    ("Concepts", "library:concept-list"),
+    ("Search", "library:search"),
+    ("Embedding pipeline", "library:embedding-dashboard"),
+]
+
+
+_original_get_app_list = admin.site.get_app_list
+
+
+def _get_app_list_with_library_links(request, app_label=None):
+    app_list = _original_get_app_list(request, app_label)
+    for app in app_list:
+        if app["app_label"] != "library":
+            continue
+        for name, url_name in _NEO4J_ADMIN_LINKS:
+            try:
+                url = reverse(url_name)
+            except NoReverseMatch:
+                continue
+            app["models"].append(
+                {
+                    "name": name,
+                    "object_name": name,
+                    "perms": {
+                        "add": False,
+                        "change": True,
+                        "delete": False,
+                        "view": True,
+                    },
+                    "admin_url": url,
+                    "add_url": None,
+                    "view_only": True,
+                }
+            )
+    return app_list
+
+
+admin.site.get_app_list = _get_app_list_with_library_links