PDF invoice reports + SMTP email sending

PDF Reports:
- Professional invoice HTML renderer (company header, partner address,
  styled line items, totals, Odoo-purple branding, A4 @page CSS)
- wkhtmltopdf installed in Docker runtime stage for real PDF generation
- Print button on invoice form (opens PDF in new tab)
- Exported HtmlToPDF/RenderInvoiceHTML for cross-package use

SMTP Email:
- SendEmail + SendEmailWithAttachments with MIME multipart support
- Base64 file attachments
- Config via ODOO_SMTP_HOST/PORT/USER/PASSWORD/FROM env vars
- LoadSMTPConfig helper, nil auth for relay servers

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/tools/email.go

@@ -1,10 +1,13 @@
 package tools
 
 import (
+	"encoding/base64"
 	"fmt"
 	"log"
 	"net/smtp"
 	"os"
+	"strconv"
+	"strings"
 )
 
 // SMTPConfig holds email server configuration.
@@ -16,26 +19,52 @@ type SMTPConfig struct {
 	From     string
 }
 
+// Attachment represents an email file attachment.
+type Attachment struct {
+	Filename    string
+	ContentType string
+	Data        []byte
+}
+
 // LoadSMTPConfig loads SMTP settings from environment variables.
+// It first checks ODOO_SMTP_* prefixed vars, then falls back to SMTP_*.
 func LoadSMTPConfig() *SMTPConfig {
 	cfg := &SMTPConfig{
-		Host:     os.Getenv("SMTP_HOST"),
-		Port:     587,
-		User:     os.Getenv("SMTP_USER"),
-		Password: os.Getenv("SMTP_PASSWORD"),
-		From:     os.Getenv("SMTP_FROM"),
+		Port: 587,
 	}
+
+	// Prefer ODOO_SMTP_* env vars, fall back to SMTP_*
+	cfg.Host = envOr("ODOO_SMTP_HOST", os.Getenv("SMTP_HOST"))
+	cfg.User = envOr("ODOO_SMTP_USER", os.Getenv("SMTP_USER"))
+	cfg.Password = envOr("ODOO_SMTP_PASSWORD", os.Getenv("SMTP_PASSWORD"))
+	cfg.From = envOr("ODOO_SMTP_FROM", os.Getenv("SMTP_FROM"))
+
+	if v := envOr("ODOO_SMTP_PORT", os.Getenv("SMTP_PORT")); v != "" {
+		if p, err := strconv.Atoi(v); err == nil {
+			cfg.Port = p
+		}
+	}
+
 	return cfg
 }
 
-// SendEmail sends a simple email. Returns error if SMTP is not configured.
+// envOr returns the value of the named environment variable if set, otherwise fallback.
+func envOr(key, fallback string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return fallback
+}
+
+// SendEmail sends a simple HTML email without attachments.
+// Returns nil (with a log message) if SMTP is not configured.
 func SendEmail(cfg *SMTPConfig, to, subject, body string) error {
 	if cfg.Host == "" {
 		log.Printf("email: SMTP not configured, would send to=%s subject=%s", to, subject)
-		return nil // Silently succeed if not configured
+		return nil
 	}
 
-	msg := fmt.Sprintf("From: %s\r\nTo: %s\r\nSubject: %s\r\nContent-Type: text/html; charset=utf-8\r\n\r\n%s",
+	msg := fmt.Sprintf("From: %s\r\nTo: %s\r\nSubject: %s\r\nMIME-Version: 1.0\r\nContent-Type: text/html; charset=utf-8\r\n\r\n%s",
 		cfg.From, to, subject, body)
 
 	auth := smtp.PlainAuth("", cfg.User, cfg.Password, cfg.Host)
@@ -43,3 +72,58 @@ func SendEmail(cfg *SMTPConfig, to, subject, body string) error {
 
 	return smtp.SendMail(addr, auth, cfg.From, []string{to}, []byte(msg))
 }
+
+// SendEmailWithAttachments sends an HTML email with optional file attachments.
+// If SMTP is not configured, it logs the intent and returns nil.
+func SendEmailWithAttachments(cfg *SMTPConfig, to []string, subject, bodyHTML string, attachments []Attachment) error {
+	if cfg.Host == "" {
+		log.Printf("email: SMTP not configured, would send to=%s subject=%s attachments=%d",
+			strings.Join(to, ","), subject, len(attachments))
+		return nil
+	}
+
+	addr := fmt.Sprintf("%s:%d", cfg.Host, cfg.Port)
+	boundary := "==odoo-go-boundary-42=="
+
+	var msg strings.Builder
+	msg.WriteString(fmt.Sprintf("From: %s\r\n", cfg.From))
+	msg.WriteString(fmt.Sprintf("To: %s\r\n", strings.Join(to, ", ")))
+	msg.WriteString(fmt.Sprintf("Subject: %s\r\n", subject))
+	msg.WriteString("MIME-Version: 1.0\r\n")
+
+	if len(attachments) > 0 {
+		msg.WriteString(fmt.Sprintf("Content-Type: multipart/mixed; boundary=\"%s\"\r\n\r\n", boundary))
+
+		// HTML body part
+		msg.WriteString(fmt.Sprintf("--%s\r\n", boundary))
+		msg.WriteString("Content-Type: text/html; charset=utf-8\r\n")
+		msg.WriteString("Content-Transfer-Encoding: 7bit\r\n\r\n")
+		msg.WriteString(bodyHTML)
+		msg.WriteString("\r\n")
+
+		// Attachment parts
+		for _, att := range attachments {
+			msg.WriteString(fmt.Sprintf("\r\n--%s\r\n", boundary))
+			ct := att.ContentType
+			if ct == "" {
+				ct = "application/octet-stream"
+			}
+			msg.WriteString(fmt.Sprintf("Content-Type: %s; name=\"%s\"\r\n", ct, att.Filename))
+			msg.WriteString(fmt.Sprintf("Content-Disposition: attachment; filename=\"%s\"\r\n", att.Filename))
+			msg.WriteString("Content-Transfer-Encoding: base64\r\n\r\n")
+			msg.WriteString(base64.StdEncoding.EncodeToString(att.Data))
+		}
+		msg.WriteString(fmt.Sprintf("\r\n--%s--\r\n", boundary))
+	} else {
+		msg.WriteString("Content-Type: text/html; charset=utf-8\r\n\r\n")
+		msg.WriteString(bodyHTML)
+	}
+
+	// Auth (nil if no user/password for relay servers)
+	var auth smtp.Auth
+	if cfg.User != "" {
+		auth = smtp.PlainAuth("", cfg.User, cfg.Password, cfg.Host)
+	}
+
+	return smtp.SendMail(addr, auth, cfg.From, to, []byte(msg.String()))
+}