Updates an existing leasing contract, allowing modification of terms, dates, or status.

This endpoint can be used to progress the contract through lifecycle stages,
modify financial parameters, or update contract terms. Only the fields that
need to be updated should be included in the request.

You can set or update the unpaid_threshold_amount_in_cents to override the customer's default
threshold for unpaid rent alerts for this specific contract.

Quarter Revision Index Update:
To update the revision index, use quarter_revision_index_attributes with quarter, nature, and year
to lookup the index from the database.

Valeur initiale du bail (signing revision index) correction:
To correct the informative "valeur initiale du bail", use signing_quarter_revision_index_id with the revision index public ID. This does not affect quarter_revision_index, the reference index used for the next revision.

Note that the asset_id cannot be changed through this endpoint as it
represents the fundamental property being rented. Creating a new leasing contract
would be the correct approach for changing the asset.

VAT (TVA):

• You can update vat_applicable and vat_rate to change VAT behavior on the contract
• When vat_applicable is true, vat_rate must be provided (0..100, decimals allowed)

Rent Indexation:
You can update indexation_enabled to enable or disable IRL rent indexation for this contract.
When enabled (true), the contract will be eligible for automatic annual rent indexation based
on the IRL index, provided a valid quarter_revision_index is set.

Revision Frequency:
You can update revision_frequency_in_years to change the rent revision frequency:

• 1: Annual revision (default)
• 3: Triennial revision (for commercial leases)

First Call Only:
Set first_call_only to true when only managing the move-in (mise en location).
Only the first rent call will be generated, with no recurring billing lines.
Mutually exclusive with rental_transfer.

Tenants and Guarantors:
Use tenant_ids / guarantor_ids (arrays of profile public IDs) to replace the tenants
or guarantors of the contract. Provide them in the JSON body, either at the root or inside
the leasing_contract object. Pass an empty array to remove all current associations.
The tenants and guarantors objects returned by GET are read-only and ignored on update.