refactor(lite): remove dead backend artifact-contract/resolver scaffold

lite_backend_artifact_{contract,resolver}.{cpp,h} (~1,960 lines) were
app-linked but never invoked: all 14 public entry points
(evaluateLiteBackendArtifactContract/Resolver, evaluateLiteBackendActivation-
Readiness, the resolve*/...Name helpers) had zero callers in the app, the
lite_smoke tool, build scripts, or surviving tests. The real backend load
path (LiteClientBridge::linkedSdxl) uses direct litelib_* externs, and the
DRAGONX_ENABLE_LITE_BACKEND symbol check is done in CMake against the symbols
inventory (FATAL_ERROR on a missing symbol) — not via these C++ files. The
files were saturated with churn markers (disabled / dry-dispatch / scaffold).

- Delete the four artifact files and their 8 CMakeLists references.
- Drop the orphaned test cruft in test_phase4.cpp: the contract include,
  5 type aliases, and 3 never-called helpers (heapConstructPlanResult,
  makeReadyLiteBackendArtifactProvenance, liteBackendArtifactContractHasIssue)
  left over from the already-removed bridge-runtime tests.
- Correct the CLAUDE.md lite-wallet description (it credited these files with
  backend validation that CMake actually performs) and drop the stale
  lite_bridge_runtime mention.

Both variants build; full test suite passes; source-hygiene check clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_phase4.cpp

@@ -20,7 +20,6 @@
 #include "ui/windows/mining_tab_helpers.h"
 #include "util/amount_format.h"
 #include "util/payment_uri.h"
-#include "wallet/lite_backend_artifact_contract.h"
 #include "wallet/lite_owned_string.h"
 #include "wallet/lite_wallet_controller.h"
 #include "wallet/lite_wallet_gateway.h"
@@ -98,11 +97,6 @@ void writeTestFile(const fs::path& path, const std::string& content)
     output << content;
 }
 
-using LiteBackendArtifactContractInput = dragonx::wallet::LiteBackendArtifactContractInput;
-using LiteBackendArtifactContractIssue = dragonx::wallet::LiteBackendArtifactContractIssue;
-using LiteBackendArtifactContractLinkMode = dragonx::wallet::LiteBackendArtifactContractLinkMode;
-using LiteBackendArtifactContractResult = dragonx::wallet::LiteBackendArtifactContractResult;
-using LiteBackendArtifactContractStatus = dragonx::wallet::LiteBackendArtifactContractStatus;
 
 
 
@@ -266,42 +260,6 @@ using LiteBackendArtifactContractStatus = dragonx::wallet::LiteBackendArtifactCo
 
 
 
-template <typename T, typename Factory>
-std::unique_ptr<T> heapConstructPlanResult(Factory&& factory)
-{
-    void* storage = ::operator new(sizeof(T));
-    try {
-        return std::unique_ptr<T>(::new (storage) T(factory()));
-    } catch (...) {
-        ::operator delete(storage);
-        throw;
-    }
-}
-
-
-dragonx::wallet::LiteBackendArtifactProvenanceMetadata makeReadyLiteBackendArtifactProvenance()
-{
-    dragonx::wallet::LiteBackendArtifactProvenanceMetadata provenance;
-    provenance.ownerReady = true;
-    provenance.metadataProvided = true;
-    provenance.source = "test-fixture";
-    provenance.builder = "phase4-tests";
-    provenance.sourceRevision = "test-revision";
-    provenance.artifactSetId = "phase1-contract";
-    provenance.redacted = true;
-    return provenance;
-}
-
-
-bool liteBackendArtifactContractHasIssue(
-    const LiteBackendArtifactContractResult& result,
-    LiteBackendArtifactContractIssue issue)
-{
-    for (const auto& issueInfo : result.issues) {
-        if (issueInfo.issue == issue) return true;
-    }
-    return false;
-}
 
 int g_liteBridgeRuntimeFakeCallCount = 0;
 int g_liteBridgeRuntimeTrackedFreeCount = 0;