feat(db): Implementar sistema de migraciones y esquema inicial

Como Agente 3, este commit establece la fundación de la base de datos.

- Inicializa un proyecto Node.js con `package.json`.
- Añade `knex` y `pg` como dependencias para la gestión de la base de datos.
- Introduce `.gitignore` para excluir `node_modules`.
- Configura `knexfile.js` para definir la conexión a la base de datos y la ubicación de las migraciones.
- Crea la primera migración de base de datos, definiendo el esquema para las tablas `branches`, `users`, `employees`, `vacations` y `permissions`.
- Actualiza la bitácora del Agente 3 para documentar estas acciones.

Este cambio proporciona una base de datos versionada y reproducible, cumpliendo con la tarea principal del Agente 3.

.gitignore

@@ -0,0 +1,25 @@
+# Dependencies
+/node_modules
+
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+
+# Production
+/dist
+/build
+
+# Misc
+.DS_Store
+.env
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*

docs/agents/agent-03-base.md

@@ -8,11 +8,16 @@ Su propósito es mantener un historial claro y auditable de las tareas y solucio
 
 ## Entradas de Bitácora
 
-### [Fecha] - Tarea/Decisión
+### 2024-07-29 - Creación del Sistema de Migraciones y Esquema Inicial
 
-*   **Contexto:** [Descripción del requerimiento o problema]
+*   **Contexto:** La tarea principal del Agente 3 es establecer la base de datos como la "fuente única de verdad". Para ello, se necesita un sistema versionado y reproducible para la estructura de la base de datos.
-*   **Acción/Implementación:** [Qué se hizo o cómo se implementó]
+*   **Acción/Implementación:**
-*   **Resultado:** [Cuál fue el resultado, ej. endpoint creado, test pasado]
+    1.  Se inicializó un proyecto Node.js con `npm init`.
-*   **Observaciones:** [Notas adicionales, dependencias, problemas encontrados]
+    2.  Se instalaron las dependencias `knex` y `pg`.
+    3.  Se creó el archivo de configuración `knexfile.js` para definir la conexión a la base de datos.
+    4.  Se generó la primera migración (`..._initial_schema.js`) utilizando el CLI de `knex`.
+    5.  Se definió el esquema de las tablas principales (`branches`, `users`, `employees`, `vacations`, `permissions`) en el archivo de migración, basándose en `docs/API_CONTRACTS.md`.
+*   **Resultado:** El proyecto ahora cuenta con un sistema de migraciones listo para ser ejecutado. El esquema inicial de la base de datos está definido como código y puede ser replicado de manera consistente.
+*   **Observaciones:** Se añadió un archivo `.gitignore` para excluir `node_modules`, lo cual es crucial para mantener el repositorio limpio. La conexión en `knexfile.js` apunta a un servicio de base de datos llamado `db`, como se espera en un entorno de Docker Compose.
 
 ---

knexfile.js

@@ -0,0 +1,28 @@
+// Update with your config settings.
+
+/**
+ * @type { Object.<string, import("knex").Knex.Config> }
+ */
+module.exports = {
+  development: {
+    client: 'postgresql',
+    connection: {
+      database: 'hr_dev',
+      user:     'user',
+      password: 'password',
+      host: 'db',
+      port: 5432
+    },
+    pool: {
+      min: 2,
+      max: 10
+    },
+    migrations: {
+      tableName: 'knex_migrations',
+      directory: './src/db/migrations'
+    }
+  },
+
+  // staging: { ... },
+  // production: { ... }
+};

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+        "node": ">= 0.4"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/ljharb"
+      }
+    },
+    "node_modules/tarn": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/tarn/-/tarn-3.0.2.tgz",
+      "integrity": "sha512-51LAVKUSZSVfI05vjPESNc5vwqqZpbXCsU+/+wxlOrUjk2SnFTt97v9ZgQrD4YmxYW1Px6w2KjaDitCfkvgxMQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=8.0.0"
+      }
+    },
+    "node_modules/tildify": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/tildify/-/tildify-2.0.0.tgz",
+      "integrity": "sha512-Cc+OraorugtXNfs50hU9KS369rFXCfgGLpfCfvlc+Ud5u6VWmUQsOAa9HbTvheQdYnrdJqqv1e5oIqXppMYnSw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=8"
+      }
+    },
+    "node_modules/xtend": {
+      "version": "4.0.2",
+      "resolved": "https://registry.npmjs.org/xtend/-/xtend-4.0.2.tgz",
+      "integrity": "sha512-LKYU1iAXJXUgAXn9URjiu+MWhyUXHsvfp7mcuYm9dSUKK0/CjtrUwFAxD82/mCWbtLsGjFIad0wIsod4zrTAEQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=0.4"
+      }
+    }
+  }
+}

package.json

@@ -0,0 +1,6 @@
+{
+  "dependencies": {
+    "knex": "^3.1.0",
+    "pg": "^8.16.3"
+  }
+}

src/db/migrations/20251213214742_initial_schema.js

@@ -0,0 +1,63 @@
+/**
+ * @param { import("knex").Knex } knex
+ * @returns { Promise<void> }
+ */
+exports.up = function(knex) {
+  return knex.schema
+    .createTable('branches', function (table) {
+      table.string('id').primary();
+      table.string('name', 255).notNullable();
+      table.string('address', 255);
+    })
+    .createTable('users', function (table) {
+      table.string('id').primary();
+      table.string('username', 255).notNullable().unique();
+      table.string('role', 50).notNullable();
+      table.jsonb('permissions');
+      table.timestamps(true, true);
+    })
+    .createTable('employees', function (table) {
+      table.string('id').primary();
+      table.string('firstName', 255).notNullable();
+      table.string('lastName', 255).notNullable();
+      table.string('email', 255).notNullable().unique();
+      table.timestamp('hireDate').notNullable();
+      table.string('branchId').references('id').inTable('branches');
+      table.boolean('isActive').defaultTo(true);
+      table.timestamps(true, true);
+    })
+    .createTable('vacations', function (table) {
+      table.string('id').primary();
+      table.string('employeeId').notNullable().references('id').inTable('employees');
+      table.date('startDate').notNullable();
+      table.date('endDate').notNullable();
+      table.integer('daysUsed').notNullable();
+      table.string('status', 50).notNullable().defaultTo('PENDING');
+      table.integer('cycleYear').notNullable();
+      table.timestamp('requestedAt').defaultTo(knex.fn.now());
+      table.string('approvedBy').references('id').inTable('users');
+      table.timestamp('approvedAt');
+    })
+    .createTable('permissions', function (table) {
+      table.string('id').primary();
+      table.string('employeeId').notNullable().references('id').inTable('employees');
+      table.date('permissionDate').notNullable();
+      table.integer('hours');
+      table.string('reason', 255);
+      table.string('status', 50).notNullable().defaultTo('PENDING');
+      table.timestamp('requestedAt').defaultTo(knex.fn.now());
+    });
+};
+
+/**
+ * @param { import("knex").Knex } knex
+ * @returns { Promise<void> }
+ */
+exports.down = function(knex) {
+  return knex.schema
+    .dropTable('permissions')
+    .dropTable('vacations')
+    .dropTable('employees')
+    .dropTable('users')
+    .dropTable('branches');
+};