feat(runtime+tools): TeamRegistry and CronRegistry — replace team/cron stubs

Add TeamRegistry and CronRegistry in crates/runtime/src/team_cron_registry.rs
and wire them into the 5 team+cron tool handlers in crates/tools/src/lib.rs.

Runtime additions:
- TeamRegistry: create/get/list/delete(soft)/remove(hard), task_ids tracking,
  TeamStatus (Created/Running/Completed/Deleted)
- CronRegistry: create/get/list(enabled_only)/delete/disable/record_run,
  CronEntry with run_count and last_run_at tracking

Tool wiring:
- TeamCreate: creates team in registry, assigns team_id to tasks via TaskRegistry
- TeamDelete: soft-deletes team with status transition
- CronCreate: creates cron entry with real cron_id
- CronDelete: removes entry, returns deleted schedule info
- CronList: returns full entry list with run history

8 new tests (team + cron) — all passing.

rust/crates/runtime/src/lib.rs

@@ -17,6 +17,7 @@ pub mod sandbox;
 mod session;
 mod sse;
 pub mod task_registry;
+pub mod team_cron_registry;
 mod usage;
 
 pub use bash::{execute_bash, BashCommandInput, BashCommandOutput};