Admin write-CRUD, Home Assistant connector config, wiring audit

Three requested phases.

1) Admin section (SDD §8.7) — MudBlazor inline-dialog CRUD, consistent pattern,
   delete guards, snackbar feedback, shared Confirm helper:
   - Energy types: create/edit/delete (blocks delete when meters reference it).
   - Meters: create/edit/delete; recomputes consumption when mode/baseline
     changes (NormalizationService over a fresh factory context, in a tx);
     delete cascades data (consumption+readings are Restrict → removed first).
   - A meter's ingest sources: manage on the meter-detail Sources tab
     (add/edit/delete MQTT/Tasmota/HA sources with typed config).
   - Tariffs: full CRUD (scope/component/value/validity).
   - Cost categories: CRUD + member management (meter or energy-type members).
   - Connectors: ingestion_endpoint CRUD (MQTT broker + Home Assistant);
     secrets referenced by env-var name only, never stored.
   - Settings: read-only effective-config view (settings are env-driven and
     reproducible, so an editable form would change nothing — kept honest).
   PV role is now editable on meters (MeterMeta.SetRole can clear a role).

2) Read Home Assistant — extracted a shared public HaEndpointConfig (was a
   private record in the worker), added HaConnectionTester (powers the connector
   "Test connection": checks base URL + env-resolved token, optionally reads one
   entity). Configuring an HA connector + an HA source on a meter drives the
   existing REST-poll worker end to end. (WebSocket push stays a future
   optimization; REST poll already reads HA.)

3) Wiring/placeholder audit — swept every OnClick/Href: all handlers are real,
   all internal links resolve to real routes, no TODO/stub/placeholder code.
   Fixed one genuine gap: MainLayout had no drawer toggle, so the nav was
   unreachable on narrow screens — added a hamburger button.

Tests: +6 (MeterMeta.SetRole role-removal; HaConnectionTester fail-closed
guard branches with a throwing HttpClientFactory proving no network on bad
config); render test now covers all admin routes. 69 Core + 45 Integration =
114 green. Live-verified in Docker: all admin pages 200, drawer toggle present,
Settings shows real effective config.

Claude-Session: https://claude.ai/code/session_01Lz2RqAsnQhetqWNoCDfexK

src/App/Components/Layout/MainLayout.razor

@@ -8,6 +8,8 @@
 
 <MudLayout>
     <MudAppBar Elevation="1" Dense="true">
+        <MudIconButton Icon="@Icons.Material.Filled.Menu" Color="Color.Inherit" Edge="Edge.Start"
+                       OnClick="@(() => _drawerOpen = !_drawerOpen)" aria-label="Toggle navigation" />
         <MudIcon Icon="@Icons.Material.Filled.Bolt" Class="mr-2" />
         <MudText Typo="Typo.h6">MeterVault</MudText>
         <MudSpacer />