feat: Add recency boost support to SearchRequest

[raphaeldelio]

Summary

Adds recency boost support to the Java SDK's SearchRequest, enabling control over memory decay in search results.

Changes

• SearchRequest: Added 8 recency boost fields with builder support
• LongTermMemoryService: Include recency params in search payload
• Added 4 unit tests for recency boost functionality

Usage

SearchRequest request = SearchRequest.builder()
    .text("query")
    .recencyBoost(true)
    .recencySemanticWeight(0.7)
    .recencyRecencyWeight(0.3)
    .serverSideRecency(true)
    .build();

---

Note

Low Risk
Low risk: changes are additive optional fields and request-payload wiring for search, plus tests. Main impact is that search requests may now include new/previously-ignored parameters (recency_*, server_side_recency, distance_threshold) when set, which can change search results.

Overview
Adds recency-boost tuning controls to SearchRequest (new recency_* weights/half-lives plus server_side_recency) with getters/setters, builder methods, and toString updates.

Updates LongTermMemoryService.searchLongTermMemories to include distance_threshold and any provided recency parameters in the JSON payload, and adds unit + integration tests asserting these fields are serialized and accepted in search calls.

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