fix(site-runtime): resolve SiteRuntime-004..011 — deploy-after-persist, remove reflection, deterministic IDs, non-blocking startup, dedicated script scheduler, config-change detection, semantic trust-model check

src/ScadaLink.SiteRuntime/Repositories/SyntheticId.cs

@@ -0,0 +1,35 @@
+namespace ScadaLink.SiteRuntime.Repositories;
+
+/// <summary>
+/// SiteRuntime-007: deterministic synthetic-ID generation for site-local artifacts.
+///
+/// The site SQLite tables are keyed by name rather than an auto-increment integer, but
+/// the shared repository contracts (<c>IExternalSystemRepository</c>,
+/// <c>INotificationRepository</c>) expose integer-keyed lookups. A synthetic integer ID
+/// is therefore derived from the entity name. It MUST be stable across process restarts
+/// — <see cref="string.GetHashCode()"/> is randomized per process on .NET Core and so
+/// cannot be used.
+/// </summary>
+internal static class SyntheticId
+{
+    // FNV-1a 32-bit constants.
+    private const uint FnvOffsetBasis = 2166136261;
+    private const uint FnvPrime = 16777619;
+
+    /// <summary>
+    /// Computes a deterministic, process-stable positive 31-bit integer ID for the
+    /// given name using the FNV-1a hash over its UTF-8 bytes.
+    /// </summary>
+    public static int From(string name)
+    {
+        var hash = FnvOffsetBasis;
+        foreach (var b in System.Text.Encoding.UTF8.GetBytes(name))
+        {
+            hash ^= b;
+            hash *= FnvPrime;
+        }
+
+        // Mask to a positive 31-bit value so the ID is always non-negative.
+        return (int)(hash & 0x7FFFFFFF);
+    }
+}