AlgoScan

The minimum balance requirement (MBR) was discussed in six places, with
the contributions of assets, apps, and boxes restated in more than one
file, and with separate statements about when a transaction fails for
not meeting the requirement.

Define the MBR of an account once, in Account State, as the base
requirement plus a contribution per resource, with each term pointing at
the section that specifies it. Keep the per-resource increments in the
sections describing those resources, and remove their duplicates.

State the failure condition once, in the account state validity
conditions, which already applied to all transaction types. The
condition there covered only assets; it now uses the account's full MBR,
and a second condition covers MaximumMinimumBalance, which was defined
as a parameter but never used.

Remove the claim that a box opcode fails when the application account
cannot cover the new requirement. The requirement is enforced once the
top-level transaction completes, so only the MBR change is immediate.

docs: post quantum account

docs: box rw access, mutable app setting, crypto opcodes, block load and congestion, lsig and txn pay-per-size, hb discount

fnet5 is the protocol AF's FNet runs. It extends v41 with the parameter
changes go-algorand released as ConsensusV42, restated rather than derived
from v42, so fnet5 stays pinned to the values FNet runs with.

Also adds the V41 -> fnet5 upgrade path.