feat(core): extend SearchResult type with snippet and imports

[prosdev]

Summary

Implements #69 - Third sub-issue of Epic #66 (Richer Search Results)

Changes

packages/core/src/vector/types.ts

• Added SearchResultMetadata interface with typed fields
• Updated SearchResult to use SearchResultMetadata instead of Record<string, unknown>

packages/core/src/vector/store.ts

• Updated search() to cast parsed metadata to SearchResultMetadata

packages/core/src/indexer/utils/documents.ts

• Added snippet and imports to prepareDocumentsForEmbedding()
• Added snippet and imports to prepareDocumentForEmbedding()

SearchResultMetadata Fields

interface SearchResultMetadata {
  path?: string;       // File path
  type?: DocumentType | string;
  language?: string;
  name?: string;
  startLine?: number;
  endLine?: number;
  exported?: boolean;
  signature?: string;
  docstring?: string;
  snippet?: string;    // NEW: from #67
  imports?: string[];  // NEW: from #68
  [key: string]: unknown;  // Extensible
}

Features

✅ Typed metadata fields with IDE autocomplete
✅ Backward compatible (all fields optional)
✅ Extensible via index signature for custom use cases
✅ snippet and imports now flow through to search results

Testing

• ✅ 1265 tests passing
• ✅ TypeScript compiles without errors
• ✅ Biome linting passes

Related Issues

• Closes Extend SearchResult type with snippet and imports #69
• Part of Epic Epic: Richer Search Results #66
• Depends on Store code snippets during indexing #67 (snippet) and Track import/export relationships during indexing #68 (imports)