fix(dron): Ejecutor funcional + tabla events

Cambios:
- ejecutor.rb: Corregir lectura de output con Open3
- bitacora_db.rb: Agregar métodos crear_evento/actualizar_evento (public)
- dron_db.rb: Corregir conversión de PG::Result a Hash (.first.to_h)
- vigilante.rb: Corregir formato de fecha en dashboard
- migrations/004: Crear tabla bitacoras.events para Bitácora Web

Pruebas:
- dron lanzar --evento AUTO --nota "Test" -- echo "hola" ✅
- dron flota ✅
- dron salud ✅

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

adn/tools/db/migrations/004_create_events_table.rb

@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+# Migración 004: Crear tabla events para Bitácora Web
+# ====================================================
+# Esta tabla almacena eventos visibles en la Bitácora Web
+# Es el medio de comunicación donde los drones dejan registro de su actividad
+
+require_relative '../core/bitacora_db'
+
+module BitacorasDB
+  module Migrations
+    class CreateEventsTable
+      def self.up
+        BitacorasDB::BitacoraDB.with_connection do |db|
+          # Crear tabla
+          db.instance_variable_get(:@connection).exec(<<~SQL)
+            CREATE TABLE IF NOT EXISTS bitacoras.events (
+              id              SERIAL PRIMARY KEY,
+              nodo_id         INTEGER NOT NULL REFERENCES bitacoras.nodos(id),
+              descripcion     TEXT NOT NULL,
+              estado          VARCHAR(10) NOT NULL DEFAULT '⏳',
+              inicio          VARCHAR(10) NOT NULL,
+              fin             VARCHAR(10),
+              modo            VARCHAR(10) DEFAULT 'A',
+              metadata        JSONB DEFAULT '{}'::jsonb,
+              created_at      TIMESTAMP DEFAULT NOW(),
+              updated_at      TIMESTAMP DEFAULT NOW()
+            )
+          SQL
+
+          # Crear índices
+          db.instance_variable_get(:@connection).exec("CREATE INDEX IF NOT EXISTS idx_events_nodo ON bitacoras.events(nodo_id)")
+          db.instance_variable_get(:@connection).exec("CREATE INDEX IF NOT EXISTS idx_events_estado ON bitacoras.events(estado)")
+          db.instance_variable_get(:@connection).exec("CREATE INDEX IF NOT EXISTS idx_events_inicio ON bitacoras.events(inicio)")
+          db.instance_variable_get(:@connection).exec("CREATE INDEX IF NOT EXISTS idx_events_metadata ON bitacoras.events USING GIN(metadata)")
+
+          # Enable RLS
+          db.instance_variable_get(:@connection).exec("ALTER TABLE bitacoras.events ENABLE ROW LEVEL SECURITY")
+
+          # Policies
+          db.instance_variable_get(:@connection).exec("DROP POLICY IF EXISTS events_insert ON bitacoras.events")
+          db.instance_variable_get(:@connection).exec("CREATE POLICY events_insert ON bitacoras.events FOR INSERT WITH CHECK (true)")
+
+          db.instance_variable_get(:@connection).exec("DROP POLICY IF EXISTS events_select ON bitacoras.events")
+          db.instance_variable_get(:@connection).exec("CREATE POLICY events_select ON bitacoras.events FOR SELECT USING (true)")
+
+          db.instance_variable_get(:@connection).exec("DROP POLICY IF EXISTS events_update ON bitacoras.events")
+          db.instance_variable_get(:@connection).exec("CREATE POLICY events_update ON bitacoras.events FOR UPDATE USING (true)")
+        end
+        puts "✅ Tabla bitacoras.events creada"
+      end
+
+      def self.down
+        BitacorasDB::BitacoraDB.with_connection do |db|
+          db.instance_variable_get(:@connection).exec("DROP TABLE IF EXISTS bitacoras.events CASCADE")
+        end
+        puts "✅ Tabla bitacoras.events eliminada"
+      end
+    end
+  end
+end
+
+if __FILE__ == $PROGRAM_NAME
+  BitacorasDB::Migrations::CreateEventsTable.up
+end