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/block-scanner.ts

@@ -4,9 +4,9 @@
  * Parses fenced code blocks with attributes:
  *   ```lang id=xxx role=xxx as=xxx
  *
- * - `role` dispatches to content scanners (stat, stat-template, spark-table)
+ * - `role` dispatches to content scanners (declare, spark-table)
  * - `as` controls rendering (none, codeblock, md-table, md-card, md-dice)
- * - `id` is used for cross-references (template names, file paths)
+ * - `id` is used for cross-references (file paths)
  */
 
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