- Detect Falcon (pqsig) signed companions from the raw msgpack, since
  algokit's decodeSignedTransaction drops pqsig, and require 3x the minimum
  fee for each. Previously such groups passed validation at 1x and were
  then rejected by the network.
- Accept unsigned transactions with or without the "TX" prefix.
- Collapse the three group-id checks into one: every transaction must
  carry the group id recomputed from the submitted transactions.
- Rely on the request DTO (2..16 base64 entries) instead of re-checking
  array length in the service.
- Sign the re-encoded sponsor transaction directly; drop the per-envelope
  unsignedEncoded copy and the dead try/catch around groupTransactions.
- Use new Address(...) like the rest of the service instead of encodeAddress.
- Deduplicate sponsorship test fixtures and table-drive the sponsor field
  checks; add a DTO validation test.
- Add on-chain e2e coverage: sponsored ed25519 (2x) and Falcon (4x) payments
  confirm with the user paying no fee, and a Falcon group 1 µALGO short is
  rejected by both the endpoint and algod simulation.

Quantum signers need a higher fee than the dApp estimated, so the wallet
raises it and regroups, which changed every txID and made the signed-txn
check reject a signature the wallet had already returned.

The check now ignores fee and group ID when matching each transaction,
requires the returned fee to be at least the requested one, and requires
the group ID the raised fees imply, so a group can't be split, joined or
created. Also rejects a Pera Web connect callback with no addresses.