Fix Database Sizes grid: scrollbar, filter handlers, per-file VLF count

- Enable horizontal scrollbar (was Disabled, clipping new columns)
- Unify all column filter buttons to DatabaseSizesFilter_Click (existing
  columns used FinOpsFilter_Click, causing split filter state)
- VLF count: filter sys.dm_db_log_info by file_id so each log file gets
  its own count instead of the whole-database total (Dashboard + Lite)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: erikdarlingdata