1.3.0

• Search now returns documents instead of chunks: Engine.Search takes a SearchConfig and returns DocumentResults, each carrying the matched chunks ranked best first.
• Added SearchConfig with Query, TaskType, MinRelevance, MaxDocuments, and MaxChunks, using plain values with defaults of keep all, 20 documents, and 3 chunks per document.
• Result scores are now a 0 to 1 relevance (higher is closer), consistent with MinRelevance.
• Made the search algorithm replaceable through a public search.Searcher interface, injectable via Config.Searcher.
• Added a public core/search package holding SearchConfig, SearchResult, and DocumentResult.
• Capped the internal chunk fetch at 4096 (sqlite-vec's KNN limit) so search stays bounded on large indexes.
• Added three runnable examples (basic, searchconfig, postgres) with a shared sample file set.
• Refreshed the README, architecture, and chunking docs to describe the search flow, and trimmed the todo to the format-support roadmap.