fix(target): explain the JavaScript directory analysis route (#733)

docs/user-visible-errors.csv

@@ -7,7 +7,7 @@ harm_rank,location,trigger,current_copy,user_risk,proposed_replacement,implement
 6,src/domain/errors.ts:AnalysisProtocolError,Application protocol fails,Raw constructor message,Can expose protocol internals,"Analysis returned an unreadable result. Retry once; if it continues, run `rea doctor`.",implemented,focused assertions passed; full `npm run check` passed
 7,src/domain/errors.ts:HopperProcessError,Analysis subprocess stops,"Hopper bridge stopped unexpectedly with code {exitCode}",Exposes provider bridge and process code,"Analysis could not start or stopped unexpectedly. Run `rea doctor`, then try again.",implemented,focused assertions passed; full `npm run check` passed
 8,src/domain/errors.ts:HopperStartError,Analysis subprocess cannot start,Hopper application bridge could not be started,Exposes provider and bridge implementation,"Analysis could not start or stopped unexpectedly. Run `rea doctor`, then try again.",implemented,focused assertions passed; full `npm run check` passed
-9,src/domain/errors.ts:BinaryTargetError,Target cannot open,"Cannot open artifact: {reason}",May expose raw reason and lacks checks,"REA could not open that app or binary. Check that the path exists, is readable, and points to a supported file.",implemented,focused assertions passed; full `npm run check` passed
+9,src/domain/errors.ts:BinaryTargetError,Target cannot open,"Cannot open artifact: {reason}",May expose raw reason and lacks checks,"Preserve the target admission reason; directories name analyze_javascript_application and rea analyze as available alternatives.",implemented,focused assertions passed; full `npm run check` passed
 10,src/domain/errors.ts:ConfigurationError,Environment configuration invalid,Raw constructor message,May expose provider-specific variables and lacks recovery,"REA configuration is invalid. Run `rea doctor` and fix the reported setting.",implemented,focused assertions passed; full `npm run check` passed
 11,src/domain/errors.ts:ArtifactOperationError,Artifact inventory or extraction fails,"Artifact {operation} failed: {reason} at {logicalPath} (declared_sha256=...)",Exposes paths hashes and internal reason,"Reason-specific plain message with safe recovery step.",implemented,focused assertions passed; full `npm run check` passed
 12,src/domain/errors.ts:EvidenceFileError,Evidence file operation fails,"Evidence bundle {operation} failed: {reason}",Internal reason token gives weak recovery,"Reason-specific plain message with safe recovery step.",implemented,focused assertions passed; full `npm run check` passed