Add Sprints 46-59: governance, porting foundation, and language graduation prep (Steps 689-828)

Sprints 46-58 implement the cross-language porting foundation: language-to-IR
adapters, equivalence checking, gate validation, legacy ingestion, managed/dynamic
families, low-level/logic-actor semantics, debug workflow tooling, AST-native
family tools, Rust/CPP raising tools, system-level orchestration, query family,
and porting gates. Sprint 59 adds the governance layer (policy packs, review
boards, waiver packets, ambiguity triage, decision ledger) with the
whetstone_review_porting_decision MCP tool.

Also includes: sprint plans 46-130, MCP taskitem pipeline scripts,
CLAUDE.md, docs, and full test matrix (steps 689-828).

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

editor/src/cpp_ir/CppErrorModelMapping.h

@@ -0,0 +1,38 @@
+#pragma once
+// Step 713: error model mapping policy.
+
+#include <string>
+
+#include <nlohmann/json.hpp>
+
+#include "SemanticCoreIR.h"
+
+struct CppErrorModelDecision {
+    std::string profile;
+    std::string resultType; // expected, status_or, exceptions
+    bool panicTranslatedToTerminate = false;
+};
+
+class CppErrorModelMapping {
+public:
+    static CppErrorModelDecision map(const SemanticCoreIR& ir,
+                                     const std::string& profile = "safe-first") {
+        CppErrorModelDecision d;
+        d.profile = profile;
+        if (profile == "interop-first") d.resultType = "status_or";
+        else if (profile == "perf-first") d.resultType = "expected";
+        else d.resultType = "expected";
+
+        const std::string dump = ir.contracts.dump();
+        d.panicTranslatedToTerminate = dump.find("panic") != std::string::npos;
+        return d;
+    }
+
+    static nlohmann::json toJson(const CppErrorModelDecision& d) {
+        return {
+            {"profile", d.profile},
+            {"resultType", d.resultType},
+            {"panicTranslatedToTerminate", d.panicTranslatedToTerminate}
+        };
+    }
+};