docs: refresh Kaspa signing transaction reference

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Summary

• refresh the English and Chinese kaspaSignTransaction reference pages in the developer portal
• document the current request fields, defaults, and response shape from the SDK source
• add source-backed flow selection and troubleshooting notes for streaming, blind signing, and previous-transaction verification

Coverage

• packages/core/src/api/kaspa/KaspaSignTransaction.ts
• packages/core/src/types/api/kaspaSignTransaction.ts
• packages/core/__tests__/kaspaSignTransaction.test.ts
• packages/shared/src/HardwareError.ts

Knowledge gaps addressed

• outdated parameter requirements and defaults
• missing refTxs, payload, gas, and useTweak documentation
• missing guidance for KaspaPrevTxIdMismatch, firmware upgrade errors, and protocol selection