docs: complete XML doc coverage (returns, summaries, inheritdoc)

Resolve all 622 issues flagged by the enhanced CommentChecker: add missing
<returns> tags (incl. the standard phrasing on non-generic Task methods),
add missing <summary> tags, and replace misused/redundant <inheritdoc/> on
members that override or implement nothing with real documentation.
Documentation-only — no behavior change; solution builds clean.

src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Validation/ValidationService.cs

@@ -45,6 +45,7 @@ public class ValidationService
     /// </summary>
     /// <param name="configuration">The flattened configuration to validate.</param>
     /// <param name="sharedScripts">Optional list of shared scripts for validation context.</param>
+    /// <returns>A merged <see cref="ValidationResult"/> aggregating all pipeline stage outcomes.</returns>
     public ValidationResult Validate(FlattenedConfiguration configuration, IReadOnlyList<ResolvedScript>? sharedScripts = null)
     {
         ArgumentNullException.ThrowIfNull(configuration);
@@ -68,6 +69,7 @@ public class ValidationService
     /// Validates that flattening produced a non-empty configuration.
     /// </summary>
     /// <param name="configuration">The flattened configuration to validate.</param>
+    /// <returns>A <see cref="ValidationResult"/> with errors or warnings if the configuration is empty or missing a name; otherwise success.</returns>
     public static ValidationResult ValidateFlatteningSuccess(FlattenedConfiguration configuration)
     {
         var errors = new List<ValidationEntry>();
@@ -97,6 +99,7 @@ public class ValidationService
     /// Canonical names must be unique within their entity type (attributes, alarms, scripts).
     /// </summary>
     /// <param name="configuration">The flattened configuration to validate.</param>
+    /// <returns>A <see cref="ValidationResult"/> with errors for each duplicate canonical name, or success.</returns>
     public static ValidationResult ValidateNamingCollisions(FlattenedConfiguration configuration)
     {
         var errors = new List<ValidationEntry>();
@@ -114,6 +117,7 @@ public class ValidationService
     /// Validates that all scripts compile successfully using the ScriptCompiler.
     /// </summary>
     /// <param name="configuration">The flattened configuration to validate.</param>
+    /// <returns>A <see cref="ValidationResult"/> with errors for each script that fails compilation.</returns>
     public ValidationResult ValidateScriptCompilation(FlattenedConfiguration configuration)
     {
         var errors = new List<ValidationEntry>();
@@ -138,6 +142,7 @@ public class ValidationService
     /// Alarm trigger configs are JSON with an "attributeName" field referencing a canonical attribute name.
     /// </summary>
     /// <param name="configuration">The flattened configuration to validate.</param>
+    /// <returns>A <see cref="ValidationResult"/> with errors for any alarm whose trigger references a missing attribute.</returns>
     public static ValidationResult ValidateAlarmTriggerReferences(FlattenedConfiguration configuration)
     {
         var errors = new List<ValidationEntry>();
@@ -167,6 +172,7 @@ public class ValidationService
     /// Validates that script trigger configurations reference existing attributes.
     /// </summary>
     /// <param name="configuration">The flattened configuration to validate.</param>
+    /// <returns>A <see cref="ValidationResult"/> with errors for any script whose trigger references a missing attribute.</returns>
     public static ValidationResult ValidateScriptTriggerReferences(FlattenedConfiguration configuration)
     {
         var errors = new List<ValidationEntry>();
@@ -209,6 +215,7 @@ public class ValidationService
     /// </list>
     /// </summary>
     /// <param name="configuration">The flattened configuration to validate.</param>
+    /// <returns>A <see cref="ValidationResult"/> with errors and warnings from all expression trigger checks.</returns>
     public static ValidationResult ValidateExpressionTriggers(FlattenedConfiguration configuration)
     {
         var errors = new List<ValidationEntry>();
@@ -302,6 +309,7 @@ public class ValidationService
     /// configuration. Returns <c>null</c> on malformed JSON or a missing key.
     /// </summary>
     /// <param name="triggerConfigJson">The trigger configuration JSON to parse.</param>
+    /// <returns>The expression string, or <c>null</c> if absent or the JSON is malformed.</returns>
     internal static string? ExtractExpressionFromTriggerConfig(string? triggerConfigJson)
     {
         if (string.IsNullOrWhiteSpace(triggerConfigJson))
@@ -330,6 +338,7 @@ public class ValidationService
     /// looks well-formed.
     /// </summary>
     /// <param name="expression">The expression to check for syntax errors.</param>
+    /// <returns>A human-readable error message if the expression is invalid; <c>null</c> if well-formed.</returns>
     internal static string? CheckExpressionSyntax(string expression)
     {
         // Advisory forbidden-API scan (TemplateEngine-006): code-region-aware so
@@ -439,6 +448,7 @@ public class ValidationService
     /// and skips keys built dynamically.
     /// </summary>
     /// <param name="expression">The expression to scan for attribute references.</param>
+    /// <returns>The distinct attribute key strings found in self-attribute accessor positions.</returns>
     internal static IEnumerable<string> ExtractAttributeReferences(string expression)
     {
         var seen = new HashSet<string>(StringComparer.Ordinal);
@@ -490,6 +500,7 @@ public class ValidationService
     /// Validates that all data-sourced attributes have connection bindings.
     /// </summary>
     /// <param name="configuration">The flattened configuration to validate.</param>
+    /// <returns>A <see cref="ValidationResult"/> with warnings for each data-sourced attribute that lacks a connection binding.</returns>
     public static ValidationResult ValidateConnectionBindingCompleteness(FlattenedConfiguration configuration)
     {
         var errors = new List<ValidationEntry>();
@@ -531,6 +542,7 @@ public class ValidationService
     /// Extracts the attribute name from a trigger configuration JSON.
     /// </summary>
     /// <param name="triggerConfigJson">The trigger configuration JSON to parse.</param>
+    /// <returns>The attribute name from the <c>attributeName</c> or legacy <c>attribute</c> key, or <c>null</c> if absent or malformed.</returns>
     internal static string? ExtractAttributeNameFromTriggerConfig(string triggerConfigJson)
     {
         // Accept both keys to stay consistent with FlatteningService.PrefixTriggerAttribute,
@@ -558,6 +570,7 @@ public class ValidationService
     /// validate" and let other checks surface the deeper problem.
     /// </summary>
     /// <param name="triggerConfigJson">The trigger configuration JSON to parse.</param>
+    /// <returns>A <see cref="HiLoSetpoints"/> record with the parsed setpoint values; any missing or non-numeric value is <c>null</c>.</returns>
     internal static HiLoSetpoints ExtractHiLoSetpoints(string triggerConfigJson)
     {
         try