refactor: move spark table parsing to directive scanner

Relocate spark table logic from the block processor to a dedicated
directive scanner. This allows spark tables to be treated as
`:md-table` directives and ensures they are processed in a second pass
after the content index is fully populated.

src/cli/completions/index.ts

@@ -2,10 +2,10 @@
  * Completion index — orchestrates all registered completion sources.
  */
 
-import { diceSource } from "./sources/dice.js";
 import { linksSource } from "./sources/links.js";
 import type { ProcessedBlocks } from "./block-processor.js";
 import type { CompletionsPayload } from "./types.js";
+import type { DirectiveScanResult } from "./directive-scanner.js";
 
 export type {
   CompletionsPayload,
@@ -18,20 +18,29 @@ export type {
 } from "./types.js";
 
 /**
- * Build completions from the content index and pre-collected blocks.
+ * Build completions from the content index, pre-collected blocks,
+ * and directive scan results.
  * Called at server startup and on any file change.
  */
 export function scanCompletions(
   index: Record<string, string>,
   blocks: ProcessedBlocks,
+  directiveResults: DirectiveScanResult[],
 ): CompletionsPayload {
-  const dice = diceSource.scan(index) as CompletionsPayload["dice"];
   const links = linksSource.scan(index) as CompletionsPayload["links"];
 
+  // Merge all directive scan results
+  const dice: CompletionsPayload["dice"] = [];
+  const sparkTables: CompletionsPayload["sparkTables"] = [];
+  for (const dr of directiveResults) {
+    dice.push(...dr.dice);
+    sparkTables.push(...dr.sparkTables);
+  }
+
   return {
     dice,
     links,
-    sparkTables: blocks.sparkTables,
+    sparkTables,
     stats: blocks.stats,
     statTemplates: blocks.statTemplates,
     statSheets: blocks.statSheets,