feat: implement filament and spool preset services with CRUD operations

- Add `FilamentService` for managing filament inventory, including creation, retrieval, updating, and deletion of filaments.
- Introduce `SpoolPresetService` for handling spool presets, allowing users to create, update, and delete their custom presets.
- Create domain models for `Filament` and `SpoolPreset` with necessary fields and methods.
- Define repository interfaces for filament and spool preset persistence.
- Implement application configuration management from environment variables.
- Set up error handling with a centralized `AppError` type.
- Build the Axum router with public and protected routes for user authentication and resource management.

backend/migrations/20240101000001_create_users.sql

@@ -0,0 +1,16 @@
+-- Migration: 001 - Criar tabela de usuários
+
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+
+CREATE TABLE users (
+    id              UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    email           TEXT NOT NULL UNIQUE,
+    password_hash   TEXT,
+    google_id       TEXT UNIQUE,
+    email_verified  BOOLEAN NOT NULL DEFAULT FALSE,
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at      TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX idx_users_email    ON users (email);
+CREATE INDEX idx_users_google_id ON users (google_id) WHERE google_id IS NOT NULL;