feat(settings): functional persisted settings — theme, accent, branding, thresholds, data (epic #29)

docs/demo-script.md

@@ -43,6 +43,9 @@ notices. See `docs/research/reinsurance-landscape.md` for the domain grounding.
 
 ## Why it is built well (talking points)
 
+- **Customizable**: Settings let you switch theme (light / dark / system), recolour the accent,
+  rename the product, set confidence thresholds, pick a default export template, and manage data
+  — all persisted and applied across the app.
 - **Modular**: parsing, OCR, classification, extraction, and reconciliation are separate,
   swappable pieces behind interfaces — add a parser or an LLM extractor without touching the UI.
 - **Extensible**: never hard-rejects; new document types and export templates slot in.

src/Reva.Core/Settings/AppSettings.cs

@@ -0,0 +1,14 @@
+namespace Reva.Core.Settings;
+
+// The app-wide, user-customizable settings. One row, persisted; loaded into RuntimeSettings at
+// startup and on every save so the whole UI reflects it.
+public sealed record AppSettings(
+    AppTheme Theme,
+    string AccentColor,          // "#rrggbb" to recolor the accent, or empty for the built-in default
+    string ProductName,
+    double ConfidenceLowMax,     // score below this renders as "Low"
+    double ConfidenceMediumMax,  // score below this renders as "Medium"; at or above is "High"
+    Guid? DefaultTemplateId)
+{
+    public static AppSettings Default => new(AppTheme.Light, string.Empty, "Reve Intelligence", 0.6, 0.85, null);
+}

src/Reva.Core/Settings/AppTheme.cs

@@ -0,0 +1,8 @@
+namespace Reva.Core.Settings;
+
+public enum AppTheme
+{
+    Light,
+    Dark,
+    System
+}

src/Reva.Core/Settings/RuntimeSettings.cs

@@ -0,0 +1,14 @@
+namespace Reva.Core.Settings;
+
+// The single in-memory source of the current app settings, so static UI helpers (branding,
+// confidence tiers) and the layout can read them without plumbing a service everywhere.
+// Set once at startup and refreshed whenever settings are saved. Reads are a lock-free
+// reference read; the value is an immutable record.
+public static class RuntimeSettings
+{
+    private static volatile AppSettings _current = AppSettings.Default;
+
+    public static AppSettings Current => _current;
+
+    public static void Set(AppSettings settings) => _current = settings;
+}

src/Reva.Infrastructure/Persistence/AppSettingsRecord.cs

@@ -0,0 +1,15 @@
+namespace Reva.Infrastructure.Persistence;
+
+// A single-row table (Id is always 1) holding the app-wide settings.
+public sealed class AppSettingsRecord
+{
+    public const int SingletonId = 1;
+
+    public int Id { get; set; } = SingletonId;
+    public string Theme { get; set; } = "Light";
+    public string AccentColor { get; set; } = string.Empty;
+    public string ProductName { get; set; } = "Reve Intelligence";
+    public double ConfidenceLowMax { get; set; } = 0.6;
+    public double ConfidenceMediumMax { get; set; } = 0.85;
+    public Guid? DefaultTemplateId { get; set; }
+}