test(deposit): cover oracle price update before execution

[Dreamstore2046]

Summary

• add a deposit-handler regression test for issue deposit_handler: market token minting uses stale pool value after price update in same ledger #253
• reuse the existing price helper through a parameterized price setter
• verify equal-sized deposits mint equal LP after a 10% oracle price update because both the incoming deposit value and current pool value move together

Notes

The current �xecute_deposit path already reads fresh oracle prices before calling get_market_token_price; this PR pins that behavior with the requested same-ledger price-move coverage.

Closes #253

Testing

• git diff --check
• Not run: cargo test -p deposit-handler second_deposit_uses_current_price_after_oracle_update -- --nocapture (cargo/
  ustup are not installed in this local environment)