Implement Laravel 4.2-inspired mail system with hexagonal DDD architecture

Add complete mail infrastructure with:
- mail-core: Domain types, errors, Mailable abstraction, ports (MailDriver, TemplateEngine)
- mail-drivers: LogDriver (development) and ArrayDriver (testing) implementations
- mail-templates: React Email theme system, pre-built components, and ReactEmailEngine

Key features:
- Effect-based async operations with typed errors
- Branded types for MessageId and EmailAddress
- Fluent Mailable API with builder pattern
- Theme-based component library (BaseLayout, Button, Alert, Badge, etc.)
- Template registry with compile/render support

Author: tonipepperoni

docs/MAIL.md

@@ -0,0 +1,23 @@
+import baseConfig from '../../../eslint.config.mjs';
+
+export default [
+  ...baseConfig,
+  {
+    files: ['**/*.json'],
+    rules: {
+      '@nx/dependency-checks': [
+        'error',
+        {
+          ignoredFiles: [
+            '{projectRoot}/eslint.config.{js,cjs,mjs}',
+            '{projectRoot}/esbuild.config.{js,ts,mjs,mts}',
+            '{projectRoot}/vite.config.{js,ts,mjs,mts}',
+          ],
+        },
+      ],
+    },
+    languageOptions: {
+      parser: await import('jsonc-eslint-parser'),
+    },
+  },
+];

libs/mail/core/eslint.config.mjs

@@ -0,0 +1,17 @@
+{
+  "name": "@gello/mail-core",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "main": "./src/index.js",
+  "types": "./src/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./src/index.d.ts",
+      "import": "./src/index.js"
+    }
+  },
+  "peerDependencies": {
+    "effect": "^3.0.0"
+  }
+}

libs/mail/core/package.json

@@ -0,0 +1,21 @@
+{
+  "name": "mail-core",
+  "$schema": "../../../node_modules/nx/schemas/project-schema.json",
+  "sourceRoot": "libs/mail/core/src",
+  "projectType": "library",
+  "tags": [],
+  "targets": {
+    "build": {
+      "executor": "@nx/esbuild:esbuild",
+      "outputs": ["{options.outputPath}"],
+      "options": {
+        "outputPath": "dist/libs/mail/core",
+        "main": "libs/mail/core/src/index.ts",
+        "tsConfig": "libs/mail/core/tsconfig.lib.json",
+        "assets": [],
+        "format": ["cjs"],
+        "generatePackageJson": true
+      }
+    }
+  }
+}

libs/mail/core/project.json

@@ -0,0 +1,50 @@
+/**
+ * @gello/mail-core
+ *
+ * Core domain types, ports, and services for the Gello mail system.
+ */
+
+// Domain Types - re-export everything
+export * from "./lib/domain/types.js"
+
+// Errors
+export {
+  MailError,
+  MailConnectionError,
+  MailValidationError,
+  MailDeliveryError,
+  TemplateError,
+  TemplateNotFoundError,
+  AttachmentError,
+  MailConfigError,
+  type MailSystemError,
+} from "./lib/domain/errors.js"
+
+// Mailable
+export {
+  type Mailable,
+  BaseMailable,
+  createSimpleMailable,
+  createTemplateMailable,
+  type MakeMailableOptions,
+} from "./lib/domain/mailable.js"
+
+// Ports
+export {
+  type MailDriver,
+  MailDriverTag,
+} from "./lib/ports/MailDriver.js"
+
+export {
+  type TemplateEngine,
+  type RenderedTemplate,
+  type CompiledTemplate,
+  TemplateEngineTag,
+} from "./lib/ports/TemplateEngine.js"
+
+// Services
+export {
+  type MailService,
+  MailTag,
+  MailServiceLive,
+} from "./lib/services/Mail.js"

libs/mail/core/src/index.ts

@@ -0,0 +1,7 @@
+import { core } from './core';
+
+describe('core', () => {
+  it('should work', () => {
+    expect(core()).toEqual('core');
+  });
+});

libs/mail/core/src/lib/core.spec.ts

@@ -0,0 +1,3 @@
+export function core(): string {
+  return 'core';
+}

libs/mail/core/src/lib/core.ts

@@ -0,0 +1,92 @@
+/**
+ * @gello/mail-core - Error Types
+ *
+ * Tagged error types for the mail system.
+ */
+
+import { Data } from "effect"
+import type { MessageId } from "./types.js"
+
+/**
+ * Base mail error
+ */
+export class MailError extends Data.TaggedError("MailError")<{
+  readonly message: string
+  readonly cause?: unknown
+}> {}
+
+/**
+ * Connection error to mail provider
+ */
+export class MailConnectionError extends Data.TaggedError("MailConnectionError")<{
+  readonly message: string
+  readonly provider: string
+  readonly cause?: unknown
+}> {}
+
+/**
+ * Email validation error (invalid address, missing fields, etc.)
+ */
+export class MailValidationError extends Data.TaggedError("MailValidationError")<{
+  readonly message: string
+  readonly field: string
+  readonly value?: unknown
+}> {}
+
+/**
+ * Delivery error from provider
+ */
+export class MailDeliveryError extends Data.TaggedError("MailDeliveryError")<{
+  readonly message: string
+  readonly messageId: MessageId
+  readonly provider: string
+  readonly providerError?: string
+  readonly statusCode?: number
+}> {}
+
+/**
+ * Template rendering error
+ */
+export class TemplateError extends Data.TaggedError("TemplateError")<{
+  readonly message: string
+  readonly template?: string
+  readonly cause?: unknown
+}> {}
+
+/**
+ * Template not found error
+ */
+export class TemplateNotFoundError extends Data.TaggedError("TemplateNotFoundError")<{
+  readonly message: string
+  readonly template: string
+}> {}
+
+/**
+ * Attachment error (file not found, too large, etc.)
+ */
+export class AttachmentError extends Data.TaggedError("AttachmentError")<{
+  readonly message: string
+  readonly filename?: string
+  readonly cause?: unknown
+}> {}
+
+/**
+ * Configuration error
+ */
+export class MailConfigError extends Data.TaggedError("MailConfigError")<{
+  readonly message: string
+  readonly field?: string
+}> {}
+
+/**
+ * Union of all mail-related errors
+ */
+export type MailSystemError =
+  | MailError
+  | MailConnectionError
+  | MailValidationError
+  | MailDeliveryError
+  | TemplateError
+  | TemplateNotFoundError
+  | AttachmentError
+  | MailConfigError