Clarify convoy vs swarm terminology in docs and code

- Convoy: Persistent tracking unit for batched work across rigs
- Swarm: Ephemeral workers on a convoy (no separate tracking)

Changes:
- docs/convoy.md: New comprehensive convoy documentation
- docs/swarm.md: Updated to explain ephemeral nature
- docs/reference.md: Replace swarm section with convoy commands
- internal/cmd/convoy.go: Clarify help text
- internal/cmd/swarm.go: Mark as deprecated

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/reference.md

@@ -220,18 +220,18 @@ gt sling <bead> <rig>        # Assign to polecat
 gt sling <bead> <rig> --molecule=<proto>
 ```
 
-### Swarm Management
+### Convoy Management (Work Tracking)
 ```bash
-gt swarm create <rig> --epic <id> --worker <name>  # Create swarm
-gt swarm create <rig> --epic <id> --worker <name> --start  # Create and start
-gt swarm start <swarm-id>       # Start a created swarm
-gt swarm status <swarm-id>      # Show swarm status
-gt swarm list [rig]             # List swarms
-gt swarm dispatch <epic-id>     # Assign next ready task to idle worker
-gt swarm land <swarm-id>        # Land completed swarm to main
-gt swarm cancel <swarm-id>      # Cancel active swarm
+gt convoy create "name" [issues...]     # Create convoy tracking issues
+gt convoy create "name" gt-a bd-b --notify mayor/  # With notification
+gt convoy add <convoy-id> <issue-id>    # Add issue (reopens if closed)
+gt convoy status [convoy-id]            # Show progress + workers (the swarm)
+gt convoy list                          # Dashboard of active convoys
+gt convoy list --active                 # Active only
 ```
 
+Note: "Swarm" is ephemeral (workers on a convoy's issues). See [Convoys](convoy.md).
+
 ### Communication
 ```bash
 gt mail inbox
@@ -334,4 +334,4 @@ bd mol bond mol-security-scan $PATROL_ID --var scope="$SCOPE"
 
 **Nondeterministic idempotence**: Any worker can continue any molecule. Steps are atomic checkpoints in beads.
 
-**Swarm coordination**: Swarms parallelize work across multiple polecats. Each swarm has an integration branch where completed tasks merge before landing to main. See [Swarms](swarm.md) for details.
+**Convoy tracking**: Convoys track batched work across rigs. A "swarm" is ephemeral - just the workers currently on a convoy's issues. See [Convoys](convoy.md) for details.