[PERF-2D] Rewrite lists endpoint: SQL aggregation + cache

[Franc3s-bot]

Rewrite /api/lists for SQL aggregation

Context

Current: loads all 96K rows → Python loops → 16s. Target: SQL GROUP BY → 200ms.

Tasks

• Rewrite aggregate_list_stats to use SQL GROUP BY with jsonb functions
• Use text-based signature for SQL grouping, compute full signature in Python only for final results
• Push faction/min_games/points filters to SQL WHERE (remove post-aggregation Python filtering)
• Wrap with get_cached_or_compute()
• Keep same API response shape (no frontend changes)
• Delete or skip analytics/new_lists.py (dead code)
• Update any tests that mock aggregate_list_stats

Acceptance criteria

• /api/lists response time <200ms uncached
• Same response data as before (no regression)