**Steps to reproduce:**
* Install the **l10n_in_reports** module.
* Go to **Accounting → Configuration → Settings**, and enable **Multi-Currencies**.
* Activate a foreign currency (e.g., USD) and set an exchange rate.
* Create a new vendor bill for an Indian vendor, setting the currency to USD.
* Add lines to the bill and apply IGST/GST taxes, then confirm the bill.
* Go to **Accounting → Reporting → GST Return Period** and initiate GSTR-2B matching for the period corresponding to the bill (using a valid JSON payload where the amounts are correctly reported in INR).

**Observed behavior:**
* The vendor bill is incorrectly marked as "Partially matched" instead of "Fully matched", accompanied by an exception stating that the total amount as per GSTR-2B does not match.

**Cause:**
* The GSTR-2B data fetched from the GST portal always reports values in the company's base currency (INR).
* The `match_bills` method was directly comparing the GSTR-2B INR amounts ( `bill_total` and `bill_taxable_value`) against the bill's `amount_total` and `amount_untaxed` fields.
* Because these fields return values in the document's foreign currency (e.g., USD), the mismatch triggers an exception and flags the bill as partially matched.

**Fix:**
* Modified the matching logic to compare GSTR-2B values against `abs(amount_total_signed)` and `abs(amount_untaxed_signed)`.
* This ensures that the amounts evaluated during reconciliation are always correctly converted and compared in the company's base currency (INR).

opw-6311097

Steps to reproduce:
---------------------------------------
1. Install Subscription Module
2. Create and Confirm SO with no recurring plan and a non-recurring product
3. Add a recurring product > Save SO > Observe the User Error
4. Now add the same recurring product through Catalog View

Observation:
---------------------------------------
No User Error raised stating
'You cannot save a sale order with recurring product and no subscription plan.'

Issue:
---------------------------------------
When you manually add a line and click 'Save', the constraint (`_constraint_subscription_plan`) is triggered and raised `UserError` https://github.com/odoo/enterprise/blob/434d88960abb5e424fdc1106fc93935d328bff78/sale_subscription/models/sale_order.py#L176-L177

When you add a product via the catalog view, it calls `_update_order_line_info` which directly creates/updates order lines, Which do not trigger the python constraint.
https://github.com/odoo/odoo/blob/ef9772bba1515bdaf5410c3af5a3e395f562d513/addons/sale/models/sale_order.py#L1926-L1933

Solution:
---------------------------------------
Two private helpers are introduced:
* `_is_exempt_from_subscription_plan_check`: single source of truth for all exempt states (draft, cancelled, upsell, and legacy upgrade orders).
* `_check_recurring_plan_mismatch`: raises a `UserError` when the order has or will have a recurring product but no subscription plan, reusing the exemption helper so both call sites stay in sync.

`_constraint_subscription_plan` is refactored to delegate to these helpers, and `_update_order_line_info` is overridden to call `_check_recurring_plan_mismatch` before the catalog update is applied, ensuring consistent validation across both entry points.

opw-6194865