fix: log swallowed exceptions in core server components

Three silent catch blocks were hiding errors with no diagnostic info:

- TreeValuesCache.MigrateDatabaseV2: log sensorId when value deserialization
  fails during V2 migration instead of silently skipping the record
- AlertScheduleProvider.LoadSchedulesFromDb: log parse error and entity id/name
  when schedule parsing fails and fallback to raw entity is used
- TreeStateSnapshot ctor: add NLog logger and log deserialization error when
  state snapshot fails to load, instead of silently setting HasData=false

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/server/HSMServer.Core/AlertSchedule/AlertScheduleProvider.cs

@@ -133,8 +133,9 @@ private void LoadSchedulesFromDatabase()
                     {
                         schedule = _parser.Parse(entity);
                     }
-                    catch
+                    catch (Exception ex)
                     {
+                        _logger.Error(ex, $"Failed to parse alert schedule. Id = {entity.Id}, Name = {entity.Name}. Using raw entity as fallback.");
                         schedule = new AlertSchedule()
                         {
                             Id = new Guid(entity.Id),

src/server/HSMServer.Core/Cache/TreeValuesCache.cs

@@ -1851,8 +1851,9 @@ private void MigrateDatabseV2()
                     {
                         val = sensor.ConvertFromJson(Encoding.UTF8.GetString(value));
                     }
-                    catch
+                    catch (Exception ex)
                     {
+                        _logger.Error(ex, $"Failed to deserialize sensor value during V2 migration. SensorId = {sensorId}");
                         continue;
                     }
 

src/server/HSMServer.Core/TreeStateSnapshot/TreeStateSnapshot.cs

@@ -1,13 +1,17 @@
 using HSMDatabase.AccessManager;
 using HSMDatabase.AccessManager.DatabaseEntities.SnapshotEntity;
 using HSMServer.Core.DataLayer;
+using NLog;
+using System;
 using System.Threading.Tasks;
 using HSMServer.Core.TreeStateSnapshot.States;
 
 namespace HSMServer.Core.TreeStateSnapshot
 {
     public sealed class TreeStateSnapshot : ITreeStateSnapshot
     {
+        private static readonly Logger _logger = LogManager.GetCurrentClassLogger();
+
         private readonly StateCollection<LastSensorState, SensorStateEntity> _sensors = new();
         private readonly StateCollection<LastKeyState, LastKeyStateEntity> _keys = new();
         private readonly ISnapshotDatabase _db;
@@ -35,8 +39,9 @@ public TreeStateSnapshot(IDatabaseCore db)
 
                     IsFinal = node.IsFinal;
                 }
-                catch 
+                catch (Exception ex)
                 {
+                    _logger.Error(ex, "Failed to deserialize tree state snapshot. Starting with empty state.");
                     HasData = false;
                 }
             }