The previous follow-up rooted path-like commands at the resolved cwd in
the shared resolvePluginStdioPaths helper, which regressed plugin
.mcp.json semantics: plugin commands are relative to the plugin package
root, so a plugin shipping ./bin/server with cwd="work" would resolve to
<pkg>/work/bin/server and ENOENT. Add a commandBase parameter defaulting
to "config-dir" (the plugin contract) and pass "cwd" only from the Codex
importer, where the OS resolves the relative command against the spawned
process cwd.
Fixes#5561
resolvePluginStdioPaths resolved a path-like command against the config
directory unconditionally, but the stdio transport spawns the subprocess
with the rooted cwd as its process cwd, so the OS resolves a relative
command from there. For cwd="server", command="./bin/mcp" that meant OMP
looked for <configDir>/bin/mcp instead of <configDir>/server/bin/mcp.
Root cwd first, then resolve path-like commands from that rooted cwd,
falling back to configDir only when no cwd is set.
Fixes#5561
Discovered plugin .mcp.json stdio servers launched relative command/cwd
values against the session cwd instead of the plugin's config directory,
breaking bundled ChatGPT/Codex plugins (e.g. Computer Use) with ENOENT
when spawning ./... from an unrelated cwd.
The claude-plugins and omp-plugins providers now resolve relative cwd and
path-like command (./ or ../) against the .mcp.json directory via a shared
resolvePluginStdioPaths helper; bare executables such as npx are left
untouched so PATH lookup still works.
Fixes#5330
roboomp