infra(argo): use decimal seed value — clap u64 parser rejects hex

alpha_train --seed is clap-typed as u64, and clap's default u64
parser only accepts decimal digits. Previous default "0x4242"
hit "invalid digit found in string" at startup.

Replace with decimal equivalent 16962 (= 0x4242) in both the
submission script default and the workflow template default.

Long-term: could add a custom clap value_parser that accepts
hex/dec/oct prefixes, but for now decimal-only matches the
foxhunt convention in other CLIs (alpha_baseline, etc.).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

scripts/argo-alpha-perception.sh

@@ -26,7 +26,7 @@ LR_CFC=3e-3
 LR_MAMBA2=1e-3
 N_TRAIN_SEQS=8000
 N_VAL_SEQS=1000
-SEED=0x4242
+SEED=16962
 WATCH=false
 
 usage() {