Cap DuckDB memory during parquet compaction to 2 GB (#758) (#762)

The in-memory DuckDB connection used for archive compaction was using the
default memory_limit (80% of physical RAM), causing multi-GB spikes when
decompressing large parquet archives. With 800 MB of compressed archives,
this easily hits 5-7 GB.

Set memory_limit=2GB so DuckDB spills to disk instead of consuming all
available RAM. Also set preserve_insertion_order=false to reduce memory
pressure since compaction has no meaningful row order.

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

Author: erikdarlingdata

Lite/Services/ArchiveService.cs

@@ -309,6 +309,14 @@ private void CompactParquetFiles()
         using var con = new DuckDBConnection("DataSource=:memory:");
         con.Open();
 
+        /* Cap memory to avoid multi-GB spikes decompressing large parquet archives.
+           DuckDB will spill excess to its temp directory automatically. */
+        using (var pragma = con.CreateCommand())
+        {
+            pragma.CommandText = "SET memory_limit = '2GB'; SET preserve_insertion_order = false;";
+            pragma.ExecuteNonQuery();
+        }
+
         var totalMerged = 0;
         var totalRemoved = 0;