Remove the unused npm distribution channel

[Teakowa]

Goal

Remove Wright's npm distribution surface so the supported installation model stays centered on the canonical native GitHub Release artifacts and the distribution channels that have real Wright consumers.

Context

Wright is a native Rust CLI (wright, wright-lsp). npm currently adds a separate maintenance surface: a meta package, per-platform packages, Node wrappers, packaging code, CI smoke coverage, npmjs.org publication, and GitHub Packages publication.

Current WrightKit usage does not show a concrete consumer that requires @wrightkit/wright or npx wright. npm therefore behaves as an unproven distribution surface rather than a product requirement.

The distribution contract established by #101 and #108 remains unchanged: GitHub Release native artifacts are canonical, and supported installers/package managers consume those artifacts rather than rebuilding Wright.

Scope

• Remove the npm meta package and platform package distribution metadata.
• Remove npm-specific wrappers and programmatic Node distribution API where they exist only to support the npm channel.
• Remove npm packaging scripts/tests that have no independent non-npm value.
• Remove npmjs.org and GitHub Packages publication from the release workflow.
• Remove npm-specific distribution smoke jobs and path triggers.
• Update distribution/release documentation so npm is no longer listed as a supported Wright installation channel.
• Preserve native GitHub Release artifacts and the existing Homebrew, WinGet, Scoop, and first-party installer contracts.

Non-goals

• Changing Wright runtime behavior or CLI semantics.
• Changing provider resolution/bootstrap behavior.
• Replacing the release pipeline with cargo-dist.
• Adding new package managers.
• Removing Node usage from unrelated tooling that has independent value.

Acceptance criteria

• Wright release/CI no longer builds, tests, attaches, or publishes npm distribution packages.
• No supported installation documentation recommends npm, npx, or @wrightkit/wright.
• Native release artifacts remain unchanged as the canonical shipped binaries.
• Homebrew, WinGet, Scoop, and existing non-npm release paths remain regression-green.
• Removing the npm path does not remove or weaken native packaged-binary verification.

Dependencies / relationships

• Follows the distribution contract established by Establish automated binary releases and the Wright v0.1 distribution contract #101 and Add first-class installation and package-manager distribution #108.
• Independent of the OPY/provider work in Run real OPY check and compile workflows through the first-party provider #245/feat: route OPY workflows through first-party provider #252; this issue must not be used to hide or bypass a native runtime defect.

Readiness

Ready. This is a distribution-surface simplification with no unresolved product or architecture decision.