feat(skills): list skills through the omp binary (skills --json)

[andrebrait]

What

The skills page now asks the omp binary for its listing: omp skills --json runs the same discovery sessions use and is parsed into the app's SkillInfo shape. The pure-Node scan stays only as a fallback for installs whose binary predates the command.

Why

The page is a pre-session surface: it must list skills with no running session, so a session-keyed source could not be relied on, and the replicated scan rules drift from omp's actual discovery (name-collision namespaces being the concrete case: skills that omp resolves as namespace/name are invisible to the replica). Keying the listing on binary capability instead of session liveness keeps the source stable per install, and every exec re-reads disk, so installs, uninstalls and toggles show immediately.

Depends on the skills CLI in oh-my-pi: can1357/oh-my-pi#12273.

Testing

• npx tsc --noEmit clean
• node --experimental-strip-types --test lib/skills-service.test.mjs: 15 pass, including new skillsFromCliPayload mapping tests (valid payload, malformed payload, provider-label mapping)
• Release build gates (build, lint, test) green in the deployment pipeline

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• npx tsc --noEmit passes
• npm run lint passes (release build gate)
• npm test passes