[codex] fix MoonBit deprecations

[bobzhang]

Summary

Fixes the MoonBit stable-toolchain deprecations and generated-file drift currently blocking PR #391.

• replace deprecated @buffer.new() calls with Buffer()
• apply current moon fmt syntax for trait and impl members (with fn ..., trait fn ...)
• migrate module manifests from moon.mod.json to moon.mod
• keep native-only process test programs in their own nested workspace so root JS/Wasm checks do not pick them up
• update helper executable paths for the current module-qualified native build layout
• make file-lock tests wait for helper process lock events instead of fixed startup sleeps
• update tests and snapshots that referenced moon.mod.json
• update the format workflow to use moon -C src/process/test_programs fmt

Validation

• moon clean && moon -C src/process/test_programs clean && MOONBIT_ASYNC_CHECK_FD_LEAK=1 moon test src/fs/lock_test.mbt
• moon check --deny-warn
• moon -C src/process/test_programs check --deny-warn
• moon check --target js --deny-warn
• moon check --target wasm --deny-warn
• moon check --target wasm-gc --deny-warn
• moon fmt --check
• moon -C src/process/test_programs fmt --check
• moon info
• MOONBIT_ASYNC_CHECK_FD_LEAK=1 moon test
• MOONBIT_ASYNC_CHECK_FD_LEAK=1 moon test --release
• MOONBIT_ASYNC_CHECK_FD_LEAK=1 moon test --enable-coverage
• moon test --target js
• moon test --release --target js
• git diff --check

[coveralls]

Coverage Report for CI Build 356

Coverage increased (+0.03%) to 79.379%

Details

• Coverage increased (+0.03%) from the base build.
• Patch coverage: 1 uncovered change across 1 file (2 of 3 lines covered, 66.67%).
• No coverage regressions found.

Uncovered Changes

File	Changed	Covered	%
src/websocket/deprecated.mbt	1	0	0.0%
Total (3 files)	3	2	66.67%

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	4190
Covered Lines:	3326
Line Coverage:	79.38%
Coverage Strength:	80289.58 hits per line

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💛 - Coveralls

[Guest0x0]

close as completed