Fix validation: faicon, Term length, duplicate checkMetadata

- Add faicon, external, namespace, package to RecognizedOptions
- Add deprecation framework for package→namespace rename
- Fix Term definition length check to sum character counts
  instead of checking sequence size
- Remove 10 duplicate checkMetadata calls on VitalDefinitions
- Add KnownOption.namespace to language module

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

Author: reid-spencer

language/shared/src/main/scala/com/ossuminc/riddl/language/KnownOptions.scala

@@ -37,6 +37,7 @@ object KnownOptions {
     KnownOption.gateway,
     KnownOption.service,
     KnownOption.package_,
+    KnownOption.namespace,
     KnownOption.technology,
     KnownOption.css,
     KnownOption.kind,
@@ -46,6 +47,7 @@ object KnownOptions {
   final val domain: Seq[String] = Seq(
     KnownOption.external,
     KnownOption.package_,
+    KnownOption.namespace,
     KnownOption.technology,
     KnownOption.css,
     KnownOption.kind,
@@ -120,6 +122,7 @@ object KnownOption {
   final val gateway = "gateway"
   final val kind = "kind"
   final val message_queue = "message-queue"
+  final val namespace = "namespace"
   final val package_ = "package"
   final val parallel = "parallel"
   final val persistent = "persistent"

passes/shared/src/main/scala/com/ossuminc/riddl/passes/validate/DefinitionValidation.scala

@@ -29,6 +29,21 @@ case class OptionSpec(
   maxArgs: Int = 0
 )
 
+/** Registry of deprecated option names and their replacements.
+  * Used to generate deprecation warnings while maintaining
+  * backward compatibility.
+  */
+object DeprecatedOptions:
+  case class Deprecation(
+    replacement: String,
+    sinceVersion: String = "1.15.0"
+  )
+
+  val registry: Map[String, Deprecation] = Map(
+    "package" -> Deprecation("namespace", "1.15.0")
+  )
+end DeprecatedOptions
+
 /** Registry of recognized RIDDL option names with their
   * specifications. Options not in this registry will produce
   * style warnings (not errors) to keep the system extensible.
@@ -78,7 +93,13 @@ object RecognizedOptions:
     ),
     "batch" -> OptionSpec(
       Seq("Projector", "Repository"), 1, 1
-    )
+    ),
+    // Icon and display options
+    "faicon" -> OptionSpec(Seq.empty, 1, 1),
+    // Domain/Context structural options
+    "external" -> OptionSpec(Seq("Domain"), 0, 0),
+    "namespace" -> OptionSpec(Seq("Domain", "Context"), 1, 1),
+    "package" -> OptionSpec(Seq("Domain", "Context"), 1, 1)
   )
 end RecognizedOptions
 
@@ -206,7 +227,7 @@ trait DefinitionValidation(using pc: PlatformContext) extends BasicValidation:
           hasDescription = true
         case t: Term =>
           check(
-            t.definition.length >= 10,
+            t.definition.map(_.s.length).sum >= 10,
             s"${t.identify}'s definition is too short. It must be at least 10 characters'",
             Warning,
             t.loc
@@ -238,6 +259,14 @@ trait DefinitionValidation(using pc: PlatformContext) extends BasicValidation:
     identity: String,
     loc: At
   ): Unit =
+    DeprecatedOptions.registry.get(option.name).foreach { dep =>
+      messages.addStyle(
+        option.loc,
+        s"Option '${option.name}' in $identity is deprecated" +
+          s" since ${dep.sinceVersion}." +
+          s" Use '${dep.replacement}' instead"
+      )
+    }
     RecognizedOptions.registry.get(option.name) match
       case Some(spec) =>
         val argCount = option.args.size

passes/shared/src/main/scala/com/ossuminc/riddl/passes/validate/ValidationPass.scala

@@ -517,7 +517,6 @@ case class ValidationPass(
     f.output.foreach { agg =>
       checkTypeExpression(agg, f, parents)
     }
-    checkMetadata(f)
   }
 
   private def validateHandler(
@@ -741,7 +740,6 @@ case class ValidationPass(
         )
       )
     }
-    checkMetadata(entity)
   }
 
   private def validateProjector(
@@ -785,15 +783,13 @@ case class ValidationPass(
           )
       }
     }
-    checkMetadata(projector)
   }
 
   private def validateRepository(
     repository: Repository,
     parents: Parents
   ): Unit = {
     checkContainer(parents, repository)
-    checkMetadata(repository)
     checkNonEmpty(
       repository.contents.filter[Schema],
       "schema",
@@ -913,7 +909,6 @@ case class ValidationPass(
             }
           }
         }
-        checkMetadata(adaptor)
       case None | Some(_) =>
         messages.addError(adaptor.errorLoc, "Adaptor not contained within Context")
     }
@@ -952,7 +947,6 @@ case class ValidationPass(
     end if
     if streamlet.handlers.isEmpty && streamlet.nonEmpty then
       messages.addMissing(streamlet.errorLoc, s"${streamlet.identify} should have a handler")
-    checkMetadata(streamlet)
   }
 
   private def validateDomain(
@@ -966,7 +960,6 @@ case class ValidationPass(
       StyleWarning,
       domain.errorLoc
     )
-    checkMetadata(domain)
   }
 
   private def validateSaga(
@@ -986,7 +979,6 @@ case class ValidationPass(
       Messages.Error,
       saga.errorLoc
     )
-    checkMetadata(saga)
   }
 
   private def validateSagaStep(
@@ -1034,7 +1026,6 @@ case class ValidationPass(
     parents: Parents
   ): Unit = {
     checkContainer(parents, c)
-    checkMetadata(c)
   }
 
   private def validateEpic(
@@ -1046,7 +1037,6 @@ case class ValidationPass(
       messages.addMissing(epic.errorLoc, s"${epic.identify} is missing a user story")
     else
       checkRef[User](epic.userStory.user, parents)
-    checkMetadata(epic)
   }
 
   private def validateGroup(