## Summary

- Add per-host rsync bandwidth limit overrides with inherit/unlimited semantics.
- Store the effective bwlimit in run metadata/results and show it in host/run detail views.
- Document recommended starting values for VPN and remote backups.

## Tests
- `.venv/bin/python manage.py makemigrations --check --dry-run`
- `.venv/bin/python manage.py test src.pobsync_backend.tests.test_django_config_source.DjangoConfigSourceTests.test_returns_effective_config_from_database src.pobsync_backend.tests.test_django_config_source.DjangoConfigSourceTests.test_host_can_disable_global_rsync_bandwidth_limit src.pobsync_backend.tests.test_configure_commands.ConfigureCommandsTests.test_configure_host_uses_global_retention_defaults src.pobsync_backend.tests.test_run_scheduled_config_source.RunScheduledConfigSourceTests.test_dry_run_applies_configured_bandwidth_limit src.pobsync_backend.tests.test_run_scheduled_config_source.RunScheduledConfigSourceTests.test_real_run_can_request_verbose_output_args --verbosity 2`
- `.venv/bin/python manage.py test src.pobsync_backend.tests.test_views.ViewTests.test_create_host_config_form_creates_host src.pobsync_backend.tests.test_views.ViewTests.test_host_detail_renders_effective_config_preview src.pobsync_backend.tests.test_views.ViewTests.test_run_detail_renders_result_payload src.pobsync_backend.tests.test_views.ViewTests.test_host_config_form_updates_host_config --verbosity 2`
- `.venv/bin/python manage.py check`

Closes #51

src/pobsync_backend/tests/test_configure_commands.py

@@ -42,6 +42,7 @@ class ConfigureCommandsTests(TestCase):
             address="web-01.example.test",
             exclude_add=["/tmp/***"],
             rsync_extra_arg=["--delete"],
+            rsync_bwlimit_kbps=4096,
             stdout=out,
         )
 
@@ -49,10 +50,12 @@ class ConfigureCommandsTests(TestCase):
         self.assertEqual(host.retention_daily, 5)
         self.assertEqual(host.excludes_add, ["/tmp/***"])
         self.assertEqual(host.rsync_extra_args, ["--delete"])
+        self.assertEqual(host.rsync_bwlimit_kbps, 4096)
 
         effective = DjangoConfigSource().effective_config_for_host("web-01")
         self.assertEqual(effective["retention"]["yearly"], 2)
         self.assertEqual(effective["excludes_effective"], ["/tmp/***"])
+        self.assertEqual(effective["rsync"]["bwlimit_kbps"], 4096)
 
     def test_configure_schedule_creates_sql_schedule(self) -> None:
         host = HostConfig.objects.create(host="web-01", address="web-01.example.test")