[Feature] Add multipattern state machine for async compilation support

[Feature] Add multipattern state machine for async compilation support

Add state machine (INIT/COMPILING/COMPILED/FALLBACK) to multipattern
for future async hyperscan compilation. Build ACISM fallback for TLD-only
patterns to allow matching while HS compiles. Mixed TLD/non-TLD patterns
use sync compile. Also update cache format to unified .hs extension.