feat(pixiv): surface user_id + url on listings (id-pairing polish)

[jackwener]

Summary

While doing instagram/facebook/pixiv coverage gap analysis, I found that pixiv listings already extract user_id and construct url per row but drop both from the column list — so opencli pixiv ranking and opencli pixiv search show table output without the IDs that would let an agent chain the result into pixiv user / pixiv illusts / pixiv detail.

This is the same class of bug as PR #1284 / #1285 / #1288 / #1289 / #1291 / #1293 — listing emits the id internally but doesn't surface it. Per the listing↔detail id pairing convention (#1297), the id columns should be visible on listings so they round-trip cleanly.

Changes

Adapter	Added columns
pixiv ranking	user_id, url
pixiv search	user_id, url
pixiv illusts	url (user_id is the arg)
pixiv user	url

The row objects already contained these fields — only the columns array projection was missing. JSON output (-f json) already exposed them, so existing scripts keep working.

Round-trip examples (after this PR)

# Pick a top-ranked artist from the daily ranking, then explore their work
opencli pixiv ranking --limit 5
# → user_id column visible
opencli pixiv user 11
opencli pixiv illusts 11

# Search → drill down into a single illust
opencli pixiv search "風景" --limit 10
# → illust_id + user_id columns both visible
opencli pixiv detail 12345678

Test plan

• npx vitest run clis/pixiv — 18/18 pass (existing tests use toMatchObject, unchanged)
• npx tsx src/build-manifest.ts — 658 entries, columns delta only
• Doc updated with explicit Output Columns table for all five pixiv commands