fix(windows): explain when Windows refuses to load the verified native addon (#6832)

When Smart App Control or an App Control policy refuses
rea-windows-x64.node, the loader reported the failure as the artifact
stage. Doctor and provider diagnostics then told the user to restore or
rebuild the native files, although their version and SHA-256 had
already matched the package manifest.

The loader now tags a failure of the module load itself, after the
manifest and digest checks pass, as the load stage. The reason keeps the
Windows error text and says that restoring the file cannot help, that
Ghidra and JADX need the native controls, that rea setup can still
register clients, and that REA must run where policy allows the file or
the maintainers can be asked about a signed build. Readiness keeps the
documented runtime_missing code for unloadable artifacts.

Setup does not depend on the native controls: with the addon
unavailable, the published 6.7.0 CLI still planned and applied the
claude_code registration, so no setup gate is changed.

Fixes #5723

docs/user-visible-errors.csv

@@ -119,3 +119,4 @@ Then rerun this installer.",implemented,verified by shell branch inspection
 90.7,src/ghidra/GhidraProviderClient.ts:projectPrimarySessionError,One procedure's decompile reaches REA_GHIDRA_DECOMPILE_TIMEOUT_SECONDS,"Ghidra decompilation of {entry} exceeded the {N}-second limit set by REA_GHIDRA_DECOMPILE_TIMEOUT_SECONDS. Only this procedure's decompilation was stopped; the Ghidra session remains usable.",Low risk; names the setting and keeps the session,Keep current copy,implemented,provider projection test and real-provider lane
 91,src/application/binaryDiagnostics/ByteEntropyService.ts,Invalid file or window,"Expected a regular file.; Selected file could not be found.; Selected byte window starts beyond the end of the file.; Selected byte window extends beyond the end of the file.; File size exceeds exact numeric offset representation.",Invalid selection cannot produce complete entropy Evidence,Choose a readable regular file and a window within its byte size,implemented,entropy service and MCP boundary tests
 92,src/domain/analysisView/byteEntropyView.ts,Non-summary entropy view,Byte entropy Evidence supports the summary view; retrieve parent Evidence for the complete block series.,Unsupported view selection,Use the summary view or retrieve complete parent Evidence,implemented,typed input rejection
+93,src/windows/WindowsNativeLoader.ts:load refused,Windows refuses to load the digest-verified native addon (for example Smart App Control or App Control policy),"REA Windows native controls are unavailable: Windows refused to load the verified native/windows/build/rea-windows-x64.node: {OS error} The file matched the package manifest, so restoring or reinstalling it will not help. ...",Previous artifact copy told users to restore or rebuild files that were already intact,"Name the OS refusal, say restoring cannot help, state that Ghidra and JADX need native controls while setup can still register clients, and point to a policy-allowed host or a maintainer-signed build",implemented,simulated loader refusal unit test; real Smart App Control block not reproduced