feat(moonbit): add moonbit_wasm_cli rule for WASI CLI components

[avrabe]

Summary

Adds a new moonbit_wasm_cli rule that generates WASI bindings using wit-bindgen moonbit, enabling MoonBit code to use proper WASI interfaces (stdout, stderr, environment, etc.) instead of MoonBit's spectest-based I/O.

Key Features

• Full WASI support pipeline: wit-bindgen → stub replacement → moon build → wasm-tools embed/new
• Uses cli_wit directly: Properly handles wit_library directory output
• Correct package imports: Adds stdout/streams imports to the run package
• Working example: //examples/moonbit_component:hello_wasi

Changes

• moonbit/private/moonbit_wasm_cli.bzl - New rule implementation
• moonbit/defs.bzl - Export new rule
• examples/moonbit_component/hello_wasi.mbt - Working example
• MODULE.bazel - Made rules_moonbit a regular dependency (not dev_dependency)
• .bazelversion - Pin to Bazel 8.2.1 for wasi_sdk compatibility
• checksums/tools/componentize-py.json - Updated checksums for canary

Usage

load("@rules_wasm_component//moonbit:defs.bzl", "moonbit_wasm_cli")

moonbit_wasm_cli(
    name = "my_cli",
    srcs = ["main.mbt"],
)

User's MoonBit code must implement run():

pub fn run() -> Result[Unit, Unit] {
  let stdout = @stdout.get_stdout()
  let bytes = string_to_bytes("Hello!\n")
  match stdout.blocking_write_and_flush(bytes) {
    Ok(_) => Ok(())
    Err(_) => Err(())
  }
}

Test plan

• Build //examples/moonbit_component:hello_wasi
• Run with wasmtime - outputs "Hello from MoonBit WASI CLI!"
• Verified checksum_updater project can use the rule