(feature) Add staff-only Django dashboard views

Add a small template-based UI for inspecting pobsync state through Django. The
dashboard shows host, schedule, snapshot, and backup run summaries, while host
detail pages show config, schedule, recent runs, and discovered snapshots.

Keep the views read-only and staff-protected, document the new dashboard URL,
and cover the routes with focused view tests.

README.md

@@ -33,6 +33,7 @@ python3 manage.py runserver
 
 The admin is available at:
 
+- http://127.0.0.1:8000/
 - http://127.0.0.1:8000/admin/
 
 Staff-only JSON endpoints are available at:
@@ -116,6 +117,7 @@ docker compose up --build web
 
 This starts Django on:
 
+- http://127.0.0.1:8010/
 - http://127.0.0.1:8010/admin/
 - http://127.0.0.1:8010/api/
 - http://127.0.0.1:8010/api/status/
@@ -150,6 +152,7 @@ base record when it is known.
 The Django retention command plans from `SnapshotRecord` instead of rediscovering snapshots from the filesystem.
 Post-backup pruning from Django also uses the SQL retention service after the completed snapshot is recorded.
 Staff-only JSON endpoints expose service status, hosts, snapshots, and backup runs for lightweight inspection.
+Staff-only dashboard views expose the same operational state through Django templates.
 
 The remaining internal engine code still contains reusable backup primitives: