fix: hb_maps:get arity misuse in genesis/delegated checkpoint flow + checkpoint data presence checks

[charmful0x]

about

following the work done on #701 i did more hb_maps:get/3 usage checks looking for default misuse.

dev_delegated_compute

hb_maps:get(<<"type">>, Snapshot, Opts) == <<"Checkpoint">> in dev_delegated_compute was calling get with the incorrect arity (passing Opts as default). fixed that to use get 4 arity. the same for Body = hb_maps:get(<<"data">>, Snapshot, Opts),

additionally for the Body patch, i added fail fast throw when the checkpoint data body isnt available

dev_genesis_wasm

the same incorrect hb_maps:get arity was used at CheckpointTargetProcID = hb_maps:get(<<"process">>, CheckpointMessage, Opts) - patched that.

additionally the import_legacy_checkpoint/0 test does:

    ?assertMatch(
        #{ <<"data">> := Data } when byte_size(Data) > 0,
        hb_maps:get(<<"snapshot">>, ProcWithCheckpoint)
    ),

but do_import/3 already validates signer/process/nonce, but it didnt validate checkpoint payload presence. so i added a data presence check at ingress (not_found rejection):

        CheckpointData = hb_maps:get(<<"data">>, CheckpointMessage, not_found, Opts),
        true ?= CheckpointData =/= not_found orelse missing_checkpoint_data,

clarity required

~genesis-wasm@1.0 restore flow goes through ~delegated-compute@1.0 (dev_genesis_wasm:normalize/3 -> dev_delegated_compute:normalize/3 -> load_state/2), so checkpoint payload assumptions should stay aligned both at ingress (do_import/3) and at restore execution (load_state/2)

should the checkpoint point integrity policy be stricter in both dev_genesis_wasm and dev_delegated_compute to restrict 'existing but empty checkpoint' data payloads (following the import_legacy_checkpoint test)?

[charmful0x]

also i added a fix for an hb_maps:get/3 opts default misuse in dev_process restore path (ensure_loaded/3): Opts was being passed as the default for <<"process">>

if process was missing, this could propagate invalid state and fail later in commitment merge/update with silent errors. now it fail fast with typed throw and validate Process as map