feat: Portal, Email Inbound, Discuss + module improvements

- Portal: /my/* routes, signup, password reset, portal user support
- Email Inbound: IMAP polling (go-imap/v2), thread matching
- Discuss: mail.channel, long-polling bus, DM, unread count
- Cron: ir.cron runner (goroutine scheduler)
- Bank Import, CSV/Excel Import
- Automation (ir.actions.server)
- Fetchmail service
- HR Payroll model
- Various fixes across account, sale, stock, purchase, crm, hr, project

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

addons/mail/models/mail_message.go

@@ -0,0 +1,53 @@
+package models
+
+import "odoo-go/pkg/orm"
+
+// initMailMessage registers the mail.message model.
+// Mirrors: odoo/addons/mail/models/mail_message.py
+func initMailMessage() {
+	m := orm.NewModel("mail.message", orm.ModelOpts{
+		Description: "Message",
+		Order:       "id desc",
+		RecName:     "subject",
+	})
+
+	m.AddFields(
+		orm.Char("subject", orm.FieldOpts{String: "Subject"}),
+		orm.Datetime("date", orm.FieldOpts{String: "Date"}),
+		orm.Text("body", orm.FieldOpts{String: "Contents"}),
+		orm.Selection("message_type", []orm.SelectionItem{
+			{Value: "comment", Label: "Comment"},
+			{Value: "notification", Label: "System notification"},
+			{Value: "email", Label: "Email"},
+			{Value: "user_notification", Label: "User Notification"},
+		}, orm.FieldOpts{String: "Type", Required: true, Default: "comment"}),
+		orm.Many2one("author_id", "res.partner", orm.FieldOpts{
+			String: "Author",
+			Index:  true,
+			Help:   "Author of the message.",
+		}),
+		orm.Char("model", orm.FieldOpts{
+			String: "Related Document Model",
+			Index:  true,
+		}),
+		orm.Integer("res_id", orm.FieldOpts{
+			String: "Related Document ID",
+			Index:  true,
+		}),
+		orm.Many2one("parent_id", "mail.message", orm.FieldOpts{
+			String:   "Parent Message",
+			OnDelete: orm.OnDeleteSetNull,
+		}),
+		orm.Boolean("starred", orm.FieldOpts{String: "Starred"}),
+		orm.Char("email_from", orm.FieldOpts{String: "From", Help: "Email address of the sender."}),
+		orm.Char("reply_to", orm.FieldOpts{String: "Reply To", Help: "Reply-To address."}),
+		orm.Char("record_name", orm.FieldOpts{
+			String: "Message Record Name",
+			Help:   "Name of the document the message is attached to.",
+		}),
+		orm.Many2many("attachment_ids", "ir.attachment", orm.FieldOpts{
+			String: "Attachments",
+			Help:   "Attachments linked to this message.",
+		}),
+	)
+}