pre-alpha 9 (257e843 2026-07-20)

• 257e8437 codegen: cleanup leftover wasm-isms
• 7f26c7cc parser: cleanup
• 33f09c24 ir: rm unused Alloc params
• e94dfede ir: remove unused ToNum
• ddeae198 builtins: cleanup unused
• 21202f5b ci: add release webhook