feat: add spark table completion and rolling support

Implement "spark tables" functionality, which allows users to roll
dice against markdown tables to retrieve specific values.

- Add `sparkTablesSource` to scan markdown files for tables starting
  with a dice notation (e.g., d6, d20).
- Implement `/spark` command in the journal to resolve and roll
  spark tables.
- Add a new message type `spark` with a dedicated UI component to
  render the results.
- Update completions API to include spark table metadata.

src/components/md-dice.tsx

@@ -62,7 +62,7 @@ customElement("md-dice", { key: "" }, (props, { element }) => {
     setRollDetail(rollResult.result.plainDetail);
     setIsRolled(true);
     if (effectiveKey()) {
-      setDiceResultToUrl(effectiveKey(), rollResult.total);
+      setDiceResultToUrl(effectiveKey(), rollResult.result.total);
     }
   };