Config wizard 'apply now' fails on bun/standalone installs — hardcoded npx openspec update

[BenNewman100]

After openspec config saves profile/workflow changes and you choose "Apply changes to this project now? → Yes", the apply step fails on installs that have no Node/npm.

• What happens: it errors with 'npx' is not recognized as an internal or external command (Windows) and prints openspec update failed. Please run it manually. The config file is saved, but the project's generated skills/commands are never regenerated — so the profile change silently doesn't take effect.
• Root cause: src/commands/config.ts runs execSync('npx openspec update', …). On installs without Node/npm — e.g. bun install -g openspec, or the standalone binary — npx doesn't exist, so the step fails even though the openspec binary itself is on PATH and works fine.
• Scope: the same execSync('npx openspec update') line is still on main, so v1.5.0 is affected too. Reproduced with openspec 1.4.1 installed via bun (~/.bun/bin/openspec.exe), with no Node/npm/npx present.
• Suggested fix: since openspec should already be on the PATH, dropping npx and just calling openspec <command> (e.g. openspec update) seems like it would fix it.

[showms]

Hey, I ran into this issue today as well while running openspec config profile to add the update skill.
The profile was saved successfully, but the apply step failed when it tried to run npx openspec update.

I've opened #1351 to fix this by invoking openspec update directly instead.