Generate HTLC Seed in the wallet instead of the bridge

### Is your feature request related to a problem?

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### Describe the solution you'd like

To improve security, generate the random seed of HTLC in the Archethic Wallet instead of in the bridge webapp

### Additional context

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### Epic

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Start by tracing where the bridge webapp currently generates the HTLC random seed and how the Archethic Wallet can provide it instead. Review the wallet-to-bridge integration and define the security boundary before making changes. Done means the seed is generated in the wallet and is no longer generated by the bridge webapp.

Written by the indexing model from the issue text.