feat(sentiment): add persistent sentiment entities, summaries, SentimentDbService and MQTT RPC refactoring

FinlyticSentiment/Entities/SectorSentimentSummaryEntity.cs

@@ -0,0 +1,28 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace FinlyticSentiment.Entities;
+
+/// <summary>
+/// Pre-aggregated real-time sentiment summary for a market sector (e.g. Technology, Healthcare).
+/// </summary>
+[Table("sector_sentiment_summaries")]
+public class SectorSentimentSummaryEntity
+{
+    [Key]
+    [MaxLength(128)]
+    public string Sector { get; set; } = string.Empty;
+
+    [Required]
+    [MaxLength(32)]
+    public string CurrentLabel { get; set; } = "NEUTRAL";
+
+    public double AverageScore { get; set; }
+
+    public int TotalArticlesCount { get; set; }
+
+    public int TotalCompaniesCount { get; set; }
+
+    public DateTime LastUpdatedUtc { get; set; } = DateTime.UtcNow;
+}