fix: cap the typed-structure dictionary in RecordEncoder

The per-encoder typedStructs dictionary (structon's random-access typed structs)
is append-only and pinned on the long-lived primary store. A wide/sparse schema
whose records vary by per-field value width mints a distinct structure per
shape×width combination and grows the dictionary unbounded, exhausting memory
(observed on a bulk-loaded table under replication catch-up).

Default maxOwnStructures to 256 (caller-overridable), bounding each dictionary.
Bumps structon to ^1.0.6, which adds the cap (uncapped by default).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: kriszyp

package-lock.json

@@ -232,7 +232,7 @@
 		"ses": "^1.15.0",
 		"stream-chain": "2.2.5",
 		"stream-json": "1.9.1",
-		"structon": "^1.0.5",
+		"structon": "^1.0.6",
 		"systeminformation": "^5.31.4",
 		"tar-fs": "^3.1.2",
 		"ulidx": "0.5.0",

package.json

@@ -96,6 +96,10 @@ export class RecordEncoder extends StructonEncoder {
 	name: string;
 	constructor(options) {
 		options.useBigIntExtension = true;
+		// Bound the per-encoder typed-structure dictionary. It is append-only and pinned on the
+		// long-lived primary store, so a wide/sparse schema (whose records vary by per-field value
+		// width) can grow it unbounded and exhaust memory. Caller-overridable; default caps it.
+		options.maxOwnStructures ??= 256;
 		/**
 		 * The base class for records that provides the read-only methods for accessing
 		 * metadata and will be assigned computed property getters. On its own, these instances