feat: add typed decode results

[cmilesio]

What

Add DecodeChain.As[T], which runs the configured command and returns a decoded value directly. It uses the same decoder, output-source selection, trimming, execution, and error wrapping as Into; Into and DecodeWith remain unchanged.

Raise the root, docs, and examples modules to Go 1.27, add minimum-version and stable CI coverage, regenerate the API docs, and retain 100% statement coverage across success and failure paths. Older toolchains can remain on the v1.1 line.

Before and after

Decoded command results no longer need a temporary variable and mutable pointer:

DecodeChain.As

Before:

var result Result
err := execx.Command("tool", "inspect").
	DecodeJSON().FromStdout().Trim().Into(&result)

After:

result, err := execx.Command("tool", "inspect").
	DecodeJSON().FromStdout().Trim().As[Result]()

The chain now describes the whole operation and produces its typed result in one expression, while Into remains available when callers intentionally want to populate an existing value.

Why

The pointer-only result shape existed because earlier Go versions could not add a result type to a method. Go 1.27 lets the decode chain own that type, making the common case concise without changing the decoder interface or error contract.

Performance

End-to-end benchmarks include subprocess startup and JSON decoding. Into and As both remain at 88,787 B and 163 allocations, and both run in the same roughly 268–283 microsecond range on linux/arm64 with one P.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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