[17.0][FIX] stock_picking_report_valued: Respect global tax rounding method

[oscars8a]

Problem:

The module was calculating picking tax amounts by always summing the
sale_price_tax field from each move line, regardless of the company's
tax_calculation_rounding_method setting. This caused discrepancies with
the related sale order when using global tax rounding (round_globally).

When round_globally is configured, sale.order calculates taxes on the
total base amount using account.tax._compute_taxes(), but the picking
was summing individual line taxes, leading to rounding differences.

Example:
I've recreated the example in Runboat.
https://www.awesomescreenshot.com/video/51310632?key=f816ff453f1917171dd799d033108b69
Sorry for my poor pronunciation

With Spanish accounting enabled, line discounts and global rounding selected.
In the Sale Order:

In the Delivery Slip Valued

Solution:

Modified StockPicking._compute_amount_all() to respect the company's
tax rounding configuration:

• When tax_calculation_rounding_method is "round_globally": Uses the
  same method as sale.order by calling account.tax._compute_taxes()
  with all lines together, ensuring taxes match the sale order exactly.

• When tax_calculation_rounding_method is "round_per_line": Keeps the
  original behavior of summing sale_price_tax from each line.

This ensures picking amounts always match the related sale order totals,
regardless of the tax rounding method configured.