Backend improvements: views, fields_get, session, RPC stubs

- Improved auto-generated list/form/search views with priority fields,
  two-column form layout, statusbar widget, notebook for O2M fields
- Enhanced fields_get with currency_field, compute, related metadata
- Fixed session handling: handleSessionInfo/handleSessionCheck use real
  session from cookie instead of hardcoded values
- Added read_progress_bar and activity_format RPC stubs
- Improved bootstrap translations with lang_parameters
- Added "contacts" to session modules list

Server starts successfully: 14 modules, 93 models, 378 XML templates,
503 JS modules transpiled — all from local frontend/ directory.

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

addons/account/models/account_tax_calc.go

@@ -0,0 +1,70 @@
+package models
+
+import "odoo-go/pkg/orm"
+
+// TaxResult holds the result of computing a tax on an amount.
+type TaxResult struct {
+	TaxID     int64
+	TaxName   string
+	Amount    float64 // tax amount
+	Base      float64 // base amount (before tax)
+	AccountID int64   // account to post tax to
+}
+
+// ComputeTax calculates tax for a given base amount.
+// Mirrors: odoo/addons/account/models/account_tax.py AccountTax._compute_amount()
+func ComputeTax(env *orm.Environment, taxID int64, baseAmount float64) (*TaxResult, error) {
+	var name string
+	var amount float64
+	var amountType string
+	var priceInclude bool
+
+	err := env.Tx().QueryRow(env.Ctx(),
+		`SELECT name, amount, amount_type, COALESCE(price_include, false)
+		 FROM account_tax WHERE id = $1`, taxID,
+	).Scan(&name, &amount, &amountType, &priceInclude)
+	if err != nil {
+		return nil, err
+	}
+
+	var taxAmount float64
+	switch amountType {
+	case "percent":
+		if priceInclude {
+			taxAmount = baseAmount - (baseAmount / (1 + amount/100))
+		} else {
+			taxAmount = baseAmount * amount / 100
+		}
+	case "fixed":
+		taxAmount = amount
+	case "division":
+		if priceInclude {
+			taxAmount = baseAmount - (baseAmount / (1 + amount/100))
+		} else {
+			taxAmount = baseAmount * amount / 100
+		}
+	}
+
+	// Find the tax account (from repartition lines)
+	var accountID int64
+	env.Tx().QueryRow(env.Ctx(),
+		`SELECT COALESCE(account_id, 0) FROM account_tax_repartition_line
+		 WHERE tax_id = $1 AND repartition_type = 'tax' AND document_type = 'invoice'
+		 LIMIT 1`, taxID,
+	).Scan(&accountID)
+
+	// Fallback: use the USt account 1776 (SKR03)
+	if accountID == 0 {
+		env.Tx().QueryRow(env.Ctx(),
+			`SELECT id FROM account_account WHERE code = '1776' LIMIT 1`,
+		).Scan(&accountID)
+	}
+
+	return &TaxResult{
+		TaxID:     taxID,
+		TaxName:   name,
+		Amount:    taxAmount,
+		Base:      baseAmount,
+		AccountID: accountID,
+	}, nil
+}