Validate v2 API boolean parameters

[caydyan]

Supersedes #3378 with the same fix rebased onto the current develop branch.

This validates v2 API boolean query parameters instead of silently coercing unsupported values to false.

Currently, prepare_args() parses booleans with str_arg.lower() in ["true", "1"], so any unsupported value becomes False. For example, /v2/transactions?show_unconfirmed=maybe can be accepted instead of returning a clear parameter error.

Details:

• Accepts only true, 1, false, and 0 for boolean route arguments.
• Returns the existing API 400 error path for unsupported boolean values.
• Validates the shared non-compose verbose query parameter before route execution.

Tests:

• python -m pytest counterpartycore/test/units/api/apiserver_test.py::test_invalid_bool_param_rejected -q
• python -m pytest counterpartycore/test/units/api/apiserver_test.py -q
• python -m ruff check counterpartycore/lib/api/apiserver.py counterpartycore/test/units/api/apiserver_test.py
• python -m ruff format --check counterpartycore/lib/api/apiserver.py counterpartycore/test/units/api/apiserver_test.py
• git diff --check

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