fix: update notice + skill name prefix

[ZeeshanAdilButt]

Summary

Two bug fixes in one PR.

1. Update notice now actually shows

The old code used Promise.race with a 500ms window after the command — fast commands (version, status, --help) exited before the npm registry responded, so no one ever saw the update banner.

New pattern: write-on-check, show-on-next-run (same as npm/Homebrew):

• showPendingUpdateNotice() reads a notice file at process start, prints the banner, deletes the file
• scheduleUpdateCheck() fires a background fetch with no await, writes the notice file if newer version found
• Notice appears before command output on the next run

2. Skill name prefix to avoid conflicts

Skill name: fields in SKILL.md were bare (search, scrape, etc.) — when two skill providers are installed, the agent sees name collisions. Updated all 13 to olostep-search, olostep-scrape, etc. The install filter normalizes both sides so --skill search and --skill olostep-search both still work.

Test plan

• npm test — 204 tests pass
• Run any command twice with an old cached version — update notice appears on second run
• olostep add skills && olostep list skills — names show as olostep-*
• olostep add skills --skill search still works