refactor: address code review findings across all projects

Apply comprehensive fixes from code reviews including:
- Extract shared utilities (SqlFormatHelper, CellValueConverter, DbDestinationBase)
- Add interface abstractions (IAuthenticationService, IDatabaseMigrator, IMisQueryBuilder)
- Implement SecureStore for encrypted secrets storage
- Fix error handling with proper HTTP status codes and logging
- Optimize double enumeration in DevEtlRegistry
- Add DataSync.Dev README for developer onboarding
- Extract filter panel base classes to reduce duplication
- Update code review docs to mark all issues as fixed

NEW/src/JdeScoping.Core/Options/SecureStoreOptions.cs

@@ -0,0 +1,40 @@
+namespace JdeScoping.Core.Options;
+
+/// <summary>
+/// Configuration options for the secure secrets store.
+/// </summary>
+public class SecureStoreOptions
+{
+    /// <summary>
+    /// Configuration section name in appsettings.json.
+    /// </summary>
+    public const string SectionName = "SecureStore";
+
+    /// <summary>
+    /// Path to the encrypted secrets store file.
+    /// Defaults to "data/secrets.json" relative to app directory.
+    /// </summary>
+    public string StorePath { get; set; } = "data/secrets.json";
+
+    /// <summary>
+    /// Path to the key file (used in development).
+    /// Defaults to "data/secrets.key" relative to app directory.
+    /// </summary>
+    public string KeyFilePath { get; set; } = "data/secrets.key";
+
+    /// <summary>
+    /// Environment variable name containing the master key (used in production).
+    /// If set and the env var exists, it takes precedence over the key file.
+    /// </summary>
+    public string MasterKeyEnvVar { get; set; } = "SCOPINGTOOL_MASTER_KEY";
+
+    /// <summary>
+    /// Whether to auto-create the store and generate a key file on first run.
+    /// </summary>
+    public bool AutoCreateStore { get; set; } = true;
+
+    /// <summary>
+    /// Whether to migrate existing secrets (RSA key, Excel passwords) on startup.
+    /// </summary>
+    public bool MigrateExistingSecrets { get; set; } = true;
+}