setup: auto-detect plugin installation scope when --scope is omitted

[Milofax]

Symptom

With the ASE plugin installed only in the Claude Code project or local scope (e.g. ase setup install --scope project), running a plain ase setup update from within the project reports an error and exits non-zero — although the update itself effectively succeeds:

• npm update -g @rse/ase updates the ASE CLI tool just fine, but
• the subsequent claude plugin update ase@ase is executed without --scope (the hard-coded option default is user), and fails because the plugin is not registered in the per-user scope.

Root cause

tool/src/ase-setup.ts registers -s, --scope with a hard-coded default of "user" for all setup sub-commands. For update, uninstall, enable, and disable this default is an assumption about where the plugin is already installed — and it is wrong whenever the installation lives in the project or local scope.

Fix

• New private method detectScope(tool): when --scope is omitted, probe the Claude Code settings files from the strongest to the weakest scope (local → project → user, resolved via the existing statuslineSettingsFile() helper) for a registered enabledPlugins entry "ase@ase" (its true/false value does not matter — even a disabled plugin is registered in that scope). The first match wins and is logged; no match falls back to user, i.e. the previous behavior.
• Wired into the update, uninstall, enable, and disable actions. An explicitly given --scope always wins. install keeps its user default (there is no existing installation to detect), mcp/statusline are untouched. For --tool copilot|codex detection immediately resolves to user, so requireClaudeScope() semantics are preserved.
• docs/usage-tool.md updated accordingly.

Testing

• npm start build (lint + tsc + plugin copy) passes cleanly.
• Functional tests with claude/npm shims and a fake $HOME:
  • project-scope-only installation, ase setup update --force → setup: detected ASE plugin installation in scope "project", runs claude plugin update ase@ase --scope project, exit 0;
  • explicit --scope user → no detection, no --scope argument (unchanged behavior);
  • no ASE registration anywhere → falls back to user (unchanged behavior);
  • ase setup enable with a settings.local.json registration ("ase@ase": false) → claude plugin enable ase@ase --scope local;
  • precedence with registrations in both local and project → local wins; a malformed settings file is skipped gracefully.

🤖 Generated with Claude Code