Search Phase 9: SDK support (TypeScript, Go, Swift)

[hegner123]

Plan: ai/plans/api/SEARCH_PLAN.md — Phase 9

Add search(query, options) method to content delivery SDKs:

• SearchOptions: type, locale, limit, offset, prefix
• SearchResult: id, content_data_id, route_slug, route_title, datatype_name/label, section/anchor, score, snippet, published_at
• SearchResponse: query, results[], total, limit, offset

TypeScript: client.search(query, opts)
Go: client.Search(ctx, query, opts)
Swift: client.search(query, options:)