Add Skyscanner flights adapter

[ankitranjan7]

Summary

• Add webcmd skyscanner flights <origin> <destination> --depart-date <YYYY-MM-DD> --return-date <YYYY-MM-DD>
• Extract visible round-trip flight cards from a warmed CloakBrowser session using Skyscanner data-testid="ticket" UI
• Detect Skyscanner human verification/CAPTCHA pages and fail with a typed auth-required path instead of returning empty rows
• Add adapter tests for URL/date validation, duplicate DOM text handling, CAPTCHA detection, and execution behavior

Command Added

webcmd skyscanner flights nyca lond --depart-date 2026-08-01 --return-date 2026-08-08 --limit 3

Columns: rank, priceText, airlines, outboundTime, outboundRoute, outboundDuration, outboundStops, returnTime, returnRoute, returnDuration, returnStops, url.

Notes

• This is intentionally browser-backed. Cold Skyscanner sessions may require the user to clear Skyscanner verification in CloakBrowser first.
• The adapter does not bypass CAPTCHA; it reuses a valid browser session and reports verification as auth-required when blocked.

Verification

• npm run test:adapter -- clis/skyscanner/flights.test.js
• npm run dev -- skyscanner flights nyca lond --depart-date 2026-08-01 --return-date 2026-08-08 --limit 3 --site-session persistent --keep-tab true --window foreground -f json
• npm run dev -- browser work verify skyscanner/flights --strict-memory
• npm run check:silent-column-drop
• npm run check:typed-error-lint
• npm run typecheck
• npm run build