Sprint 289: Integration into generate_taskitems (steps 1973-1977)

EnrichedExecutionContract, TaskitemLibraryAnnotator, AnnotatedTaskitemValidator,
DispatchJustificationReport, Sprint289IntegrationSummary. 25/25 tests passing.
Full pipeline: spec -> classifier -> selector -> advisor -> enriched contracts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

editor/src/AnnotatedTaskitemValidator.h

@@ -0,0 +1,59 @@
+#pragma once
+// Step 1975: AnnotatedTaskitemValidator
+// Validates enrichment of EnrichedExecutionContracts.
+// ValidationReport { passCount, failCount, errors (include taskDescription) }.
+// If enrichmentRequired=true, any unenriched contract is an error.
+// Also validates capabilityScore in [0,1] for enriched contracts.
+
+#include "EnrichedExecutionContract.h"
+#include <string>
+#include <vector>
+
+namespace whetstone {
+
+struct ValidationReport {
+    int passCount = 0;
+    int failCount = 0;
+    std::vector<std::string> errors;
+
+    bool allPassed() const { return failCount == 0; }
+};
+
+class AnnotatedTaskitemValidator {
+public:
+    ValidationReport validate(
+            const std::vector<EnrichedExecutionContract>& contracts,
+            bool enrichmentRequired) const {
+
+        ValidationReport report;
+
+        for (const auto& c : contracts) {
+            const std::string desc = c.taskDescription.empty()
+                ? "(unnamed task)" : c.taskDescription;
+
+            bool pass = true;
+
+            // Check enrichment requirement
+            if (enrichmentRequired && !c.isEnriched()) {
+                report.errors.push_back("task not enriched: " + desc);
+                pass = false;
+            }
+
+            // Validate fields on enriched contracts
+            if (c.isEnriched()) {
+                if (c.capabilityScore < 0.0f || c.capabilityScore > 1.0f) {
+                    report.errors.push_back(
+                        "capabilityScore out of range [0,1] for: " + desc);
+                    pass = false;
+                }
+            }
+
+            if (pass) ++report.passCount;
+            else      ++report.failCount;
+        }
+
+        return report;
+    }
+};
+
+} // namespace whetstone