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_activity.go

@@ -0,0 +1,62 @@
+package models
+
+import "odoo-go/pkg/orm"
+
+// initMailActivity registers the mail.activity model.
+// Mirrors: odoo/addons/mail/models/mail_activity.py MailActivity
+func initMailActivity() {
+	m := orm.NewModel("mail.activity", orm.ModelOpts{
+		Description: "Activity",
+		Order:       "date_deadline ASC",
+	})
+
+	m.AddFields(
+		orm.Char("res_model", orm.FieldOpts{
+			String:   "Related Document Model",
+			Required: true,
+			Index:    true,
+		}),
+		orm.Integer("res_id", orm.FieldOpts{
+			String:   "Related Document ID",
+			Required: true,
+			Index:    true,
+		}),
+		orm.Many2one("activity_type_id", "mail.activity.type", orm.FieldOpts{
+			String:   "Activity Type",
+			OnDelete: orm.OnDeleteRestrict,
+		}),
+		orm.Char("summary", orm.FieldOpts{String: "Summary"}),
+		orm.Text("note", orm.FieldOpts{String: "Note"}),
+		orm.Date("date_deadline", orm.FieldOpts{
+			String:   "Due Date",
+			Required: true,
+			Index:    true,
+		}),
+		orm.Many2one("user_id", "res.users", orm.FieldOpts{
+			String:   "Assigned to",
+			Required: true,
+			Index:    true,
+		}),
+		orm.Selection("state", []orm.SelectionItem{
+			{Value: "overdue", Label: "Overdue"},
+			{Value: "today", Label: "Today"},
+			{Value: "planned", Label: "Planned"},
+		}, orm.FieldOpts{String: "State", Default: "planned"}),
+		orm.Boolean("done", orm.FieldOpts{String: "Done", Default: false}),
+		// Odoo 19: deadline_range for flexible deadline display
+		orm.Integer("deadline_range", orm.FieldOpts{
+			String: "Deadline Range (Days)", Help: "Number of days before/after deadline for grouping",
+		}),
+	)
+
+	// action_done: mark activity as done
+	// Mirrors: odoo/addons/mail/models/mail_activity.py action_done
+	m.RegisterMethod("action_done", func(rs *orm.Recordset, args ...interface{}) (interface{}, error) {
+		env := rs.Env()
+		for _, id := range rs.IDs() {
+			env.Tx().Exec(env.Ctx(),
+				`UPDATE mail_activity SET done = true WHERE id = $1`, id)
+		}
+		return true, nil
+	})
+}