feat(search): add comprehensive Redis Query Engine support

[bsbodden]

Implement modular Search architecture with complete feature parity to redis-py:

Core Components:

• Schema and field definitions (TextField, NumericField, TagField, GeoField, VectorField, GeoShapeField)
• Query builder with fluent API and advanced query syntax
• Index management and operations (create, drop, alter, info)
• Aggregation framework with reducers and grouping
• Hybrid search combining text and vector queries
• Result parsing and formatting

Search Features:

• Full-text search with stemming, phonetic matching, and stop words
• Vector similarity search supporting FLAT, HNSW, and SVS-VAMANA algorithms
• Geospatial search with radius and polygon queries
• Numeric and tag filtering
• Aggregations with grouping, sorting, applying, and reducing
• Hybrid search with score combination (RRF, linear)
• Auto-complete/suggestions with fuzzy matching
• Spell checking and synonym management
• Query profiling and explain

Field Types:

• TextField: full-text search with weights, phonetic matching, withsuffixtrie
• NumericField: range queries with sortable option
• TagField: exact-match filtering with case sensitivity and separators
• GeoField: geospatial queries with radius search
• VectorField: vector similarity with multiple algorithms and distance metrics
• GeoShapeField: polygon-based geospatial queries

Advanced Features:

• IndexDefinition for fine-grained index control
• Query parameters for dynamic queries
• Multiple dialect support (1, 2, 3, 4)
• Cursor-based pagination for large result sets
• Score explanations and custom scorers
• Highlighting and summarization

Bug Fixes:

• Fix PARAMS handling to preserve binary vector data (don't call .to_s on values)
• Add DIALECT 2 requirement for KNN queries in Redis 8
• Add convenience API for SORTBY (:sort_by + :asc parameters)
• Fix field option ordering for proper Redis command syntax

Testing:

• Add comprehensive test suite with 44 tests across 8 test files
• Test coverage for all search features and edge cases
• Hybrid search tests with vector + text queries
• Aggregation tests with complex pipelines
• Vector similarity tests with multiple algorithms

Documentation:

• Add 6 example files demonstrating all features:
  • search_quickstart.rb: basic search operations
  • search_ft_queries.rb: advanced query syntax
  • search_aggregations.rb: aggregation pipelines
  • search_geo.rb: geospatial queries
  • search_range.rb: numeric range queries
  • search_vector_similarity.rb: vector search
  • search_with_hashes.rb: search with Redis hashes

Results: 44 tests, 215 assertions, 0 failures, 0 errors, 0 skips