fix(build): musl legs drop llvm-inprocess for a pure-static link (#7353)

[andilv]

The musl release/manual-build legs could not statically link the glibc-built in-process LLVM: versioned refs (_isoc23*@@GLIBC_2.38) and -lz3/-lxml2/-lffi system libs neither link into musl, and a forced link yields a musl+glibc hybrid that segfaults at startup.

• perry: perry-codegen no longer uses workspace = true (cargo ignores default-features = false on inherited deps); llvm-inprocess is now opt-in via default instead of perry-codegen's default feature
• workflows: musl legs build --no-default-features --features full-cli and a new Verify step asserts the binary is fully static (no INTERP)
• .cargo/config.toml: per-target rustflags prepend the musl libc.a dir (build-script -L dirs won glibc's libc.a) and disable fortify for musl C compiles (__memcpy_chk missing in musl on aarch64)

Musl binaries now shell out to LLVM tools (opt/llc) at compile time, like pre-PerryTS#7353 builds.

Summary

Changes

Related issue

Test plan

• cargo build --release clean
• cargo test --workspace --exclude perry-ui-ios --exclude perry-ui-tvos --exclude perry-ui-watchos --exclude perry-ui-gtk4 --exclude perry-ui-android --exclude perry-ui-windows passes
• (if user-facing) Added or updated a test under test-files/ or a #[test] in the affected crate
• (if CLI / stdlib / runtime API changed) Updated docs/src/
• (if touching a platform UI backend) Built -p perry-ui-<backend> locally on that platform

Screenshots / output

Checklist

• I have NOT bumped the workspace version or edited CLAUDE.md / CHANGELOG.md (maintainer handles these at merge)
• My commits follow the loose feat: / fix: / docs: / chore: prefix convention used in the log
• I've read CONTRIBUTING.md and agree to the Code of Conduct