feat(swc_cli): Implement all features for swc_cli

[kdy1]

Summary

• add real long-running swc compile --watch support with incremental --out-dir updates and --out-file rebuilds
• add --copy-files and --strip-leading-paths to the Rust CLI
• normalize --out-dir path resolution, including absolute inputs, and cover the regressions with issue tests

Why

Issue #4017 called out a few gaps in the Rust CLI compared to the older behavior: --watch was exposed but did not actually keep running, compatibility flags for copying files and stripping leading paths were missing, and out-dir path handling regressed for some inputs. This keeps the current default dist/src/... layout while restoring the requested compatibility options and watch behavior.

Validation

• git submodule update --init --recursive
• cargo fmt --all
• cargo test -p swc_cli_impl
• cargo clippy --all --all-targets -- -D warnings

Fixes #4017

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Latest commit: 3648031

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[socket-security]

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👍 No dependency changes detected in pull request

[github-actions]

Binary Sizes

File	Size
swc.linux-x64-gnu.node	27M (27776072 bytes)

Commit: ef89b66

[codspeed-hq]

Merging this PR will not alter performance

✅ 219 untouched benchmarks
⏩ 31 skipped benchmarks¹

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_{Comparing kdy1/issue-4017-cli-comment-fixes (3648031) with main (5986411)²}

Footnotes

1. 31 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (857c0b6) during the generation of this report, so 5986411 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩