[RSS1102]

Related to #2953. Based on the createCLI() approach discussed with Vitest.

Implementation

1. Generate at build time: read the public command and option definitions from vitest/node.createCLI() and package them as dist/completion/test.json.
2. Follow the selected toolchain: prefer the runnable project-local Vite+ package, including the directory selected by -C; use the global package when no runnable local CLI exists.
3. Complete in Rust: read and validate the packaged metadata without starting Node.js, loading project configuration, or triggering installation. Missing, invalid, unsupported, or version-mismatched metadata falls back to the existing completion behavior.

Capabilities

Area	Support
Shells	Bash, Zsh, Fish, and PowerShell through vp env setup
Commands	Implicit vp test and run, watch, dev, related, bench, list, doctor
Options	Long names, short aliases, negative spellings (--no-color), and nested options (--coverage.reporter)
Scope and descriptions	Command-specific options and descriptions, displayed where supported by the shell
Argument handling	Options after file filters; required/optional value positions and -- respected

Examples: vp test --reporte<Tab> → --reporter; vp test list --filesO<Tab> → --filesOnly.

Support boundary

• Both the global CLI and selected Vite+ package need a build containing this feature. No extra Vitest configuration is required.
• Support follows Vite+'s paired Vitest 5.x toolchain, currently validated with 5.0.5. Each paired dependency upgrade is checked by contract and consumer tests; arbitrary Vitest replacements are outside this guarantee.
• Older toolchains without matching metadata, including Vitest 3/4 fallback cases, retain the original completion behavior.
• Command and option-name completion only: this first implementation follows Vite+'s existing shell completion behavior. It does not provide Vitest option-value candidates (such as reporter or environment names), test/project names, or init/complete expansion. Nushell changes and test execution compatibility are outside this PR.

[RSS1102]

@liangmiQwQ @fengmk2 cc