feat: command interface — frontend-agnostic dispatch crate
Add swactor-command crate that decouples command dispatch from the
dashboard, enabling the same commands from REPL, REST, TUI, or any
future frontend.
- CommandRouter with dispatch(), CommandHandler trait, CommandMeta
- CommandRequest/CommandResponse (serde-serializable JSON protocol)
- CommandContext with Arc<Runtime> + optional StatsEnricher trait
- 9 built-in commands extracted from investigate.rs:
help, overview, workers, worker, actors, actor, hot, phases, diff,
shutdown
- REPL line parser (parse_line) with positional arg mapping
- REST adapter (from_query_params) for HTTP query parameters
- Dashboard integration: StatsEnricher impl for StatsCollector,
investigate.rs refactored to thin CommandRouter wrapper,
server.rs updated to share CommandRouter across handler threads
- 18 behavioral tests in crates/command/tests/command_api.rs
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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