refactor: replace stat-parser with declare-parser

Replace the old stat-parser logic with a new declare-parser to handle
variable declarations and tag modifiers. This includes moving the
declare-parser logic to a shared location in cli/completions to avoid
duplication between the CLI and the journal component.

src/cli/completions/index.ts

@@ -12,8 +12,8 @@ export type {
   DiceCompletion,
   LinkCompletion,
   SparkTableCompletion,
-  StatDef,
-  StatTemplate,
+  VarDeclaration,
+  TagModifier,
 } from "./types.js";
 
 /**
@@ -40,7 +40,7 @@ export function scanCompletions(
     dice,
     links,
     sparkTables,
-    stats: blocks.stats,
-    statTemplates: blocks.statTemplates,
+    declarations: blocks.declarations,
+    tagModifiers: blocks.tagModifiers,
   };
-}
+}