feat: add multi-item ingest and Reed-Solomon parity

- Multi-item ingest: each item gets its own Unix socket, Rust processes
  them sequentially into a single snapshot with separate chunk lists
- Reed-Solomon parity: rs(20,1) erasure coding for pack file groups,
  enabling single-pack-loss recovery via parity reconstruction
- Repair now attempts parity-based recovery for missing pack files
- 16 integration tests + 12 Rust unit tests all pass

ts/interfaces.ts

@@ -134,6 +134,7 @@ export interface IRepairResult {
   indexRebuilt: boolean;
   indexedChunks: number;
   staleLocksRemoved: number;
+  packsRepaired: number;
   errors: string[];
 }
 
@@ -180,6 +181,13 @@ export type TContainerArchiveCommands = {
     },
     { snapshot: ISnapshot }
   >;
+  ingestMulti: ICommandDefinition<
+    {
+      tags?: Record<string, string>;
+      items: Array<{ name: string; type: string; socketPath: string }>;
+    },
+    { snapshot: ISnapshot }
+  >;
   restore: ICommandDefinition<
     {
       snapshotId: string;