wip: add long message helpers and payload type controls

- add centralized message validation errors
- switch command handlers to return error
- add explicit long plain-text reply helpers
- support strict payload type policy with debug logging
- document versioning and changelog workflow

utils/version.go

@@ -2,7 +2,7 @@ package utils
 
 const (
 	// VersionString is the module version string.
-	VersionString = "1.0.0-rc.11"
+	VersionString = "1.0.0-rc.12"
 	// VersionMajor is the module major version.
 	VersionMajor = 1
 	// VersionMinor is the module minor version.
@@ -10,5 +10,5 @@ const (
 	// VersionPatch is the module patch version.
 	VersionPatch = 0
 	// VersionBeta is the prerelease counter for the current version.
-	VersionBeta = 11
+	VersionBeta = 12
 )