Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@magicblock-aperture/src/requests/http/simulate_transaction.rs`:
- Around line 77-82: The error message returned when rejecting unsupported
encodings is inaccurate: the conditional checks for UiAccountEncoding::Binary or
UiAccountEncoding::Base58 but the RpcError::invalid_params message only mentions
"base58 encoding not supported"; update the error text in the
RpcError::invalid_params call (in the conditional that inspects
accounts_encoding) to reflect both unsupported encodings (e.g., "binary and
base58 encodings not supported" or similar) so the message matches the checked
UiAccountEncoding variants.

In `@magicblock-processor/src/executor/processing.rs`:
- Around line 120-139: The current branch handling
ProcessedTransaction::Executed only collects
executed.loaded_transaction.accounts up to number_of_accounts, which omits any
additionally requested pubkeys and forces callers to patch accounts later;
update the code that builds the simulation request to include the requested
pubkeys (e.g., a field like simulation_request.requested_pubkeys) and here in
the match arm for ProcessedTransaction::Executed materialize those requested
accounts from the same simulated snapshot instead of only using
executed.loaded_transaction.accounts — replace the post_simulation_accounts =
executed.loaded_transaction.accounts.into_iter().take(number_of_accounts).collect()
logic with code that merges/constructs accounts by pulling each requested pubkey
from the snapshot (using the same snapshot source used by the simulator) so the
returned accounts array contains the post-simulation state for all requested
addresses.

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@magicblock-aperture/src/requests/http/simulate_transaction.rs`:
- Around line 55-125: Validate config.accounts (encoding, address count, and
parse each address into Pubkey) before calling
self.transactions_scheduler.simulate(...) so malformed params or unsupported
encodings are rejected prior to consuming scheduler work; then after simulation
use the returned TransactionSimulationResult.post_simulation_accounts map to
assemble the response for each requested pubkey (mapping missing entries to
None) instead of calling read_accounts_with_ensure (remove the fallback to
current AccountsDb), and preserve the existing behavior of returning
Some(vec![None; ...]) only when result_err.is_some() after validation and
parsing have already occurred.