Validate confirmation target

[caydyan]

Supersedes #3384 with the same fix rebased onto the current develop branch.

prepare_fee_parameters() accepted any confirmation_target value before passing it to Bitcoin Core fee estimation. The backend helper documents the valid range as 1 to 1008 blocks, but compose-time callers could pass 0, negative values, or values above 1008 and let the error surface later at the RPC layer.

This PR validates the confirmation target before calling estimatesmartfee.

Changes:

• Adds MAX_CONFIRMATION_TARGET = 1008.
• Rejects confirmation_target values below 1 or above 1008 when fee estimation will use the parameter.
• Adds regression coverage for 0, negative, and above-range values.

Tests:

• python -m pytest counterpartycore/test/units/api/composer_test.py::test_prepare_fee_parameters -q
• python -m pytest counterpartycore/test/units/api/composer_test.py -q
• python -m ruff check counterpartycore/lib/api/composer.py counterpartycore/test/units/api/composer_test.py
• python -m ruff format --check counterpartycore/lib/api/composer.py counterpartycore/test/units/api/composer_test.py
• git diff --check

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