gt spawn: fix proto ID for mol-polecat-work (gt-lwuu)

The proto ID is gt-lwuu, not mol-polecat-work. bd mol run looks up
by ID, not title. Updated spawn to use correct proto ID.

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

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

internal/cmd/spawn.go

@@ -102,8 +102,9 @@ func runSpawn(cmd *cobra.Command, args []string) error {
 	// Auto-use mol-polecat-work for issue-based spawns (Phase 3: Polecat Work Cycle)
 	// This gives polecats a structured workflow with checkpoints for crash recovery.
 	// Can be overridden with explicit --molecule flag.
+	// Note: gt-lwuu is the proto ID for mol-polecat-work
 	if spawnIssue != "" && spawnMolecule == "" {
-		spawnMolecule = "mol-polecat-work"
+		spawnMolecule = "gt-lwuu"
 	}
 
 	// Find workspace first (needed for rig inference)