feat: desacoplar launcher del registro estatico de agentes

Introduce un registro global de reglas en agents/registry.go con
Register() y GetRules(). Cada paquete de agente se auto-registra
via init(), eliminando la necesidad de editar manualmente el map
rulesRegistry en cmd/launcher/main.go.

Cambios:
- agents/registry.go: nuevo registro global con sync.RWMutex
- agents/*/agent.go: cada agente llama agents.Register() en init()
- agents/_template/agent.go: placeholder AGENT_ID_PLACEHOLDER para scaffold
- cmd/launcher/main.go: elimina rulesRegistry, usa blank imports +
  agents.GetRules() para obtener reglas por agent ID

Patron: init() + blank import (estandar Go: database/sql, image codecs)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cmd/launcher/main.go

@@ -20,9 +20,6 @@ import (
 	"github.com/spf13/cobra"
 
 	"github.com/enmanuel/agents/agents"
-	assistantagent "github.com/enmanuel/agents/agents/assistant-bot"
-	asistente2agent "github.com/enmanuel/agents/agents/asistente-2"
-	meteorologoagent "github.com/enmanuel/agents/agents/meteorologo"
 	"github.com/enmanuel/agents/internal/config"
 	"github.com/enmanuel/agents/pkg/decision"
 	"github.com/enmanuel/agents/pkg/orchestration"
@@ -31,15 +28,12 @@ import (
 	agentlog "github.com/enmanuel/agents/shell/logger"
 	orchshell "github.com/enmanuel/agents/shell/orchestration"
 	shellsecurity "github.com/enmanuel/agents/shell/security"
-)
 
-// rulesRegistry maps agent IDs to their rule factories.
-// Add a new entry here when you create a new agent package.
-var rulesRegistry = map[string]func() []decision.Rule{
-	"assistant-bot": assistantagent.Rules,
-	"asistente-2":   asistente2agent.Rules,
-	"meteorologo":   meteorologoagent.Rules,
-}
+	// Blank imports: each agent self-registers its rules via init().
+	_ "github.com/enmanuel/agents/agents/assistant-bot"
+	_ "github.com/enmanuel/agents/agents/asistente-2"
+	_ "github.com/enmanuel/agents/agents/meteorologo"
+)
 
 func main() {
 	var (
@@ -289,10 +283,13 @@ func startOrchestrator(agentBus *bus.Bus, logger *slog.Logger) (*orchHandle, err
 	return &orchHandle{orchestrator: orch, cfg: cfg}, nil
 }
 
+// rulesFor retrieves the rule factory for the given agent ID from the
+// global registry (populated by init() in each agent package).
+// Returns nil if no rules are registered (command-only bot).
 func rulesFor(agentID string, logger *slog.Logger) []decision.Rule {
-	factory, ok := rulesRegistry[agentID]
-	if !ok {
-		logger.Warn("no rules registered for agent, using empty ruleset", "id", agentID)
+	factory := agents.GetRules(agentID)
+	if factory == nil {
+		logger.Warn("no rules registered for agent, using empty ruleset (command-only)", "id", agentID)
 		return nil
 	}
 	return factory()