build: add xtask workflows

[tisonkun]

Summary

• add the cargo x build, test, and lint workflows used by fast/template and fast/macroweave
• run lint checks once and test the manifest-derived MSRV plus stable across Linux, macOS, and Windows
• preserve both debug and release build checks through cargo x build
• enable resolver v3, raise the MSRV to Rust 1.88, and remove the direct psm version workaround

Design Notes

The MSRV now follows rust-lang/stacker#149 and matches the current psm/ar_archive_writer dependency chain. The branch passes lint, debug and release builds, tests on stable and Rust 1.88, and package verification on Rust 1.88.

[tisonkun]

Looks like we should resolve rust-lang/stacker#139 first.

[tisonkun]

We can merge this as is now. But a clean solution could depend on rust-lang/stacker#149 and I'm waiting for upstream maintainer's (@nagisa) feedback on whether we may have a recent release for a fix.