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.
Refactor the completions system to support both CLI mode (via
`/__COMPLETIONS.json`) and a client-side fallback scan for dev mode.
- Implement client-side scanning of the file index for dice and headings
- Add `ensureCompletions` to allow components to await data readiness
- Update `JournalInput` to handle "no results" states in the dropdown
- Improve keyboard navigation (Tab to accept, Enter to select)
- Update dice regex to support `:md-dice[...]` syntax
hypercross