feat(client): automatic deposit (regular paymaster) flow in SdkWallet (#918)

strk20InvokeTransaction picks the paymaster flow from the actions: with a deposit it derives the
user-signed approve(pool, amount) and switches to invoke_and_apply_action (a deposit's approve must
run as the user, but apply_action executes as the paymaster); with no deposit it stays on the private
apply_action. The user signs the paymaster's typed data via the injected signer. The fee is always
folded in as a withdraw out of the pool so the proof covers it (a simulate-based exact quote is a
TODO pending AVNU support). SdkWalletConfig gains signer + userAddress. 7 tests.

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