feat(alarms): HiLo trigger type with per-band level, hysteresis, messages, overrides

Adds a new HiLo alarm trigger type with four configurable setpoints
(LoLo / Lo / Hi / HiHi). Each setpoint carries an optional priority,
deadband (for hysteresis), and operator message. The site runtime emits
AlarmStateChanged with an AlarmLevel field so consumers can differentiate
warning vs critical bands.

Plumbing:
  - new AlarmLevel enum + AlarmStateChanged.Level/Message init properties
  - AlarmTriggerEditor (Blazor) gets a HiLo render with severity tinting
  - AlarmTriggerConfigCodec extracted from the editor for testability
  - sitestream.proto carries level + message over gRPC
  - SemanticValidator enforces numeric attribute, setpoint ordering,
    non-negative deadband
  - on-trigger scripts get an Alarm global (Name/Level/Priority/Message)
    so notification routing can branch by severity
  - per-instance InstanceAlarmOverride entity + EF migration + flattening
    step + CLI commands; HiLo overrides merge setpoint-by-setpoint, binary
    types whole-replace
  - DebugView shows a Level badge + per-band message tooltip
  - App.razor auto-reloads on permanent Blazor circuit failure
  - docker/regen-proto.sh automates the proto regen workflow (the linux/arm64
    protoc segfault means generated files are checked in for now)

src/ScadaLink.Commons/Interfaces/Repositories/ITemplateEngineRepository.cs

@@ -65,6 +65,13 @@ public interface ITemplateEngineRepository
     Task UpdateInstanceAttributeOverrideAsync(InstanceAttributeOverride attributeOverride, CancellationToken cancellationToken = default);
     Task DeleteInstanceAttributeOverrideAsync(int id, CancellationToken cancellationToken = default);
 
+    // InstanceAlarmOverride
+    Task<IReadOnlyList<InstanceAlarmOverride>> GetAlarmOverridesByInstanceIdAsync(int instanceId, CancellationToken cancellationToken = default);
+    Task<InstanceAlarmOverride?> GetAlarmOverrideAsync(int instanceId, string alarmCanonicalName, CancellationToken cancellationToken = default);
+    Task AddInstanceAlarmOverrideAsync(InstanceAlarmOverride alarmOverride, CancellationToken cancellationToken = default);
+    Task UpdateInstanceAlarmOverrideAsync(InstanceAlarmOverride alarmOverride, CancellationToken cancellationToken = default);
+    Task DeleteInstanceAlarmOverrideAsync(int id, CancellationToken cancellationToken = default);
+
     // InstanceConnectionBinding
     Task<IReadOnlyList<InstanceConnectionBinding>> GetBindingsByInstanceIdAsync(int instanceId, CancellationToken cancellationToken = default);
     Task AddInstanceConnectionBindingAsync(InstanceConnectionBinding binding, CancellationToken cancellationToken = default);