fix(windows): use cross-spawn for shim-backed commands

[Hona]

The pain

• Windows shim-backed commands (.cmd / .bat) were failing across upgrade, uninstall, PR handoff, IDE install, and LSP launch.
• shell: true papers over that, but it adds quoting and process-lifecycle problems.

The solution

• Use cross-spawn in packages/opencode/src/util/process.ts for normal argv launches.
• Keep shell usage explicit.
• Route LSP launches through the shared process path and keep Process.stop(...) for Windows teardown.

Why it works

• cross-spawn handles Windows shim resolution and quoting without forcing shell semantics.
• Built-in and configured LSP commands now launch the same way.

Fixes

• Fixes Windows: opencode upgrade fails to detect installation method (returns unknown) #17295
• Fixes opencode uninstall should work for chocolatey and scoop on windows #8573
• Fixes On the Windows platform, starting from v1.2.12, /editor is unavailable. #17117
• Fixes When using lsp to inspect Python files in Windows, encounter the error: “Error: Error: ENOENT: no such file or directory, uv_spawn ‘pyright-langserver’”. #11260
• Fixes ESLint LSP server fails to auto-install on Windows #6365

[Copilot]

Pull request overview

Routes Windows install detection and package-manager upgrade commands through a shell so .cmd/.bat shims resolve correctly, and improves visibility into npm-registry update checks via additional logging.

Changes:

• Forward shell through Process.run() so Process.text()/Process.run() behave consistently when shell execution is required.
• On Windows, run install-method detection and upgrade commands with shell: true for npm/pnpm/bun/choco/scoop.
• Add info/error logging around npm-registry “latest version” lookups (including request URL and failure details).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
packages/opencode/src/util/process.ts	Passes opts.shell from Process.run() down to spawn() so callers can reliably enable shell execution.
packages/opencode/src/installation/index.ts	Enables shell routing on Windows for detection/upgrades and adds registry lookup logging for update checks.

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