feat(rightmove): add property search adapter

[YanzhongSu]

Summary

Add a public Rightmove property search adapter backed by Rightmove's location/typeahead and listing JSON endpoints.

The new opencli rightmove search [location] command supports:

• postcode / outcode / region lookup via los.rightmove.co.uk/typeahead
• postcode radius searches without external geocoding (POSTCODE^<id> + --radius)
• buy / rent channels, price filters, bedroom filters, sort, pagination offset, and limit
• advanced map-style area searches through --bbox (LAT_LONG_BOX^...) and --polygon (USERDEFINEDAREA^{"polylines":"..."})
• compact listing rows with id, address, price, bedrooms, bathrooms, agent, coordinates, and details URL

Docs are added at docs/adapters/browser/rightmove.md, and cli-manifest.json is rebuilt.

Validation

• npx vitest run --project adapter clis/rightmove/rightmove.test.js — 9/9 pass
• node dist/src/main.js validate rightmove — PASS
• npm run build — manifest compiled with 816 entries
• npm run docs:build — build complete
• git diff --check — clean

Live smoke checks against Rightmove public endpoints:

• node dist/src/main.js rightmove search 'SW1A 1AA' --radius 0.5 --limit 3 -f json
• node dist/src/main.js rightmove search W12 --sort newest --limit 2 -f json
• node dist/src/main.js rightmove search London --min-price 500000 --max-price 1000000 --min-beds 2 --sort lowest --limit 2 -f json
• node dist/src/main.js rightmove search --bbox=-0.2664,-0.1926,51.5296,51.4920 --limit 2 -f json
• node dist/src/main.js rightmove search --polygon='yblyHlen@jPvQjPgC~FcH~GgX~@oU_EePiKiKm]NsItHkHzRi@zZrCzZtCvBtOeBuHoM' --limit 2 -f json
• node dist/src/main.js rightmove search W12 --channel rent --radius 0.5 --limit 2 -f json