feat(bob): concurrent swaps

[binarybaron]

No description provided.

[binarybaron]

We should display the final state of the swap until the user acknowledges it.

[binarybaron]

We should move the "cancel timeline" from the "history" page to the "swaps" page and hide it somewhat (make it expandable).

[binarybaron]

Issue:

run_exclusive_initiation releases the initiation lock at swap_manager.rs:642 before the lock-tx is broadcast. UTXO selection happens inside the spawned task (TxLock::new → wallet.send_to_address); the wallet mutex is method-level, so two concurrent buy_xmr calls can build PSBTs from the same UTXOs.