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)

docker/regen-proto.sh

@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+#
+# Regenerates the gRPC C# files from sitestream.proto.
+#
+# Background: protoc (linux/arm64) segfaults inside our Docker build container
+# (Grpc.Tools 2.71.0). As a workaround the generated Sitestream.cs +
+# SitestreamGrpc.cs are checked into src/ScadaLink.Communication/SiteStreamGrpc/
+# and the Protobuf ItemGroup in the .csproj is commented out — Docker just
+# compiles the checked-in C# files.
+#
+# Run this script ON YOUR DEV MACHINE whenever Protos/sitestream.proto changes:
+#
+#   1. Temporarily uncomments the Protobuf ItemGroup so Grpc.Tools runs.
+#   2. dotnet build (regen writes fresh files to obj/).
+#   3. Copies the regenerated files back into SiteStreamGrpc/.
+#   4. Re-comments the Protobuf ItemGroup so Docker builds stay safe.
+#
+# Once we move to a Dockerfile base image that ships a working linux/arm64
+# protoc, this script can be retired and Docker can regen the proto on every
+# build like every other normal .NET project.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+COMM_DIR="$REPO_ROOT/src/ScadaLink.Communication"
+CSPROJ="$COMM_DIR/ScadaLink.Communication.csproj"
+GEN_DIR="$COMM_DIR/SiteStreamGrpc"
+
+echo "=== Regenerating gRPC files from sitestream.proto ==="
+
+if [[ ! -f "$CSPROJ" ]]; then
+  echo "ERROR: csproj not found at $CSPROJ" >&2
+  exit 1
+fi
+
+# Backup so we can always restore the comment state on failure.
+BACKUP="$(mktemp)"
+cp "$CSPROJ" "$BACKUP"
+trap 'cp "$BACKUP" "$CSPROJ"; rm -f "$BACKUP"; echo "Restored csproj from backup."' ERR
+
+# 1. Uncomment the Protobuf ItemGroup (strip the surrounding <!-- ... --> wrapper).
+python3 - <<PY
+import re, pathlib
+p = pathlib.Path("$CSPROJ")
+src = p.read_text()
+# Find the commented Protobuf block and unwrap it.
+new = re.sub(
+    r"<!--\s*\n(\s*<ItemGroup>\s*\n\s*<Protobuf [^>]*/>\s*\n\s*</ItemGroup>)\s*\n\s*-->",
+    r"\1",
+    src,
+    count=1,
+)
+if new == src:
+    raise SystemExit("Couldn't find commented Protobuf ItemGroup to enable.")
+p.write_text(new)
+PY
+
+# 2. Delete the stale files so any failure to regen is obvious.
+rm -f "$GEN_DIR/Sitestream.cs" "$GEN_DIR/SitestreamGrpc.cs"
+
+# 3. Regenerate by building.
+echo "Building Communication project (regen)..."
+dotnet build "$CSPROJ" --nologo -v minimal | tail -5
+
+# 4. Copy generated files back into the source tree.
+mkdir -p "$GEN_DIR"
+cp "$COMM_DIR/obj/Debug/net10.0/Protos/Sitestream.cs" "$GEN_DIR/Sitestream.cs"
+cp "$COMM_DIR/obj/Debug/net10.0/Protos/SitestreamGrpc.cs" "$GEN_DIR/SitestreamGrpc.cs"
+echo "Copied regenerated files to $GEN_DIR/"
+
+# 5. Re-comment the Protobuf ItemGroup so Docker builds keep working.
+python3 - <<PY
+import re, pathlib
+p = pathlib.Path("$CSPROJ")
+src = p.read_text()
+new = re.sub(
+    r"(\s*<ItemGroup>\s*\n\s*<Protobuf [^>]*/>\s*\n\s*</ItemGroup>)",
+    r"\n  <!--\1\n  -->",
+    src,
+    count=1,
+)
+p.write_text(new)
+PY
+
+rm -f "$BACKUP"
+trap - ERR
+
+echo ""
+echo "Done. Review and commit:"
+echo "  git diff src/ScadaLink.Communication/Protos/sitestream.proto"
+echo "  git diff src/ScadaLink.Communication/SiteStreamGrpc/"