feat: import agents_and_robots platform as unibots (Matrix-out, unibus transport)

Reemplaza el scaffold del echobot por la plataforma completa de bots traida
desde ~/DataProyects/Github/agents_and_robots tras la operacion Matrix-out:
los bots ya no hablan por Matrix sino por el bus unibus (modelo todo-rooms +
E2E via shell/transportunibus sobre github.com/enmanuel/unibus/pkg/client).

- go.mod: replace de unibus -> ../unibus y de fn-registry -> ../../../.. (paths
  relativos reajustados a la nueva ubicacion dentro de fn_registry).
- app.md: bump a 0.2.0, descripcion + arquitectura + comandos + gotchas reales.
- modulo Go conservado como github.com/enmanuel/agents (sin reescribir imports).

agents_and_robots queda archivado como museo de la era Matrix.

agents/registry.go

@@ -0,0 +1,61 @@
+// Package agents provides a global registry for agent rule factories.
+//
+// Each agent package self-registers via init() using Register.
+// The launcher retrieves rules via GetRules without importing agent
+// packages explicitly (only blank imports are needed).
+package agents
+
+import (
+	"sync"
+
+	"github.com/enmanuel/agents/pkg/decision"
+)
+
+// RulesFunc is a factory that returns the decision rules for an agent.
+type RulesFunc func() []decision.Rule
+
+var (
+	registryMu sync.RWMutex
+	registry   = make(map[string]RulesFunc)
+)
+
+// Register adds a rule factory for the given agent ID.
+// Intended to be called from init() in each agent package.
+// Panics if the same ID is registered twice (catches copy-paste errors early).
+func Register(id string, fn RulesFunc) {
+	registryMu.Lock()
+	defer registryMu.Unlock()
+
+	if _, exists := registry[id]; exists {
+		panic("agents.Register: duplicate agent id: " + id)
+	}
+	registry[id] = fn
+}
+
+// GetRules returns the rule factory for the given agent ID.
+// Returns nil if no rules are registered (the agent is command-only).
+func GetRules(id string) RulesFunc {
+	registryMu.RLock()
+	defer registryMu.RUnlock()
+	return registry[id]
+}
+
+// RegisteredIDs returns a sorted list of all registered agent IDs.
+// Useful for debugging and diagnostics.
+func RegisteredIDs() []string {
+	registryMu.RLock()
+	defer registryMu.RUnlock()
+
+	ids := make([]string, 0, len(registry))
+	for id := range registry {
+		ids = append(ids, id)
+	}
+	return ids
+}
+
+// resetRegistry clears all registrations (for testing only).
+func resetRegistry() {
+	registryMu.Lock()
+	defer registryMu.Unlock()
+	registry = make(map[string]RulesFunc)
+}