feat: harden remote serve and reuse connections

- Gate TCP serve commands with safe-by-default policies, per-key allow tokens, per-key rate limiting, and audit labels.
- Reuse authenticated encrypted remote sessions and parallelize/caches multi-browser fanout to reduce repeated handshake roundtrips.
- Increase paged native-host batch size with extension-side byte budgeting to speed large tab listings safely.
- Point install output at public Chrome Web Store / Firefox AMO listings by default, with --dev preserving unpacked workflows.
- Share search-engine metadata between CLI and SDK and bump the package/extension version to 0.16.0.
- Cover the new security, pooling, paging, install, and fanout behavior with expanded Python and extension tests.

extension/src/classes/CommandRegistry.ts

@@ -17,17 +17,33 @@ function isCommandSpec(entry: CommandEntry): entry is CommandSpec {
   return typeof entry !== "function";
 }
 
+// Fill each page up to a byte budget kept safely under the 1MB native-messaging
+// limit (extension → host). This makes paging adaptive: many small items pack
+// into one page, while a few oversized items (e.g. data-URI favicons) split
+// across pages instead of overflowing the limit.
+const PAGE_BYTE_BUDGET = 768 * 1024;
+
 export function makePagedData(items: Serializable[], page: PageRequest) {
   const total = items.length;
   const offset = Math.max(0, Number(page.offset) || 0);
   const requestedLimit = Math.max(1, Number(page.limit) || 100);
-  const limit = Math.min(requestedLimit, 1000);
-  const end = Math.min(offset + limit, total);
+  const maxCount = Math.min(requestedLimit, 1000);
+
+  let end = offset;
+  let bytes = 0;
+  while (end < total && end - offset < maxCount) {
+    const itemBytes = JSON.stringify(items[end]).length + 1; // +1 ≈ separator
+    // Always include at least one item so a single oversized item still advances.
+    if (end > offset && bytes + itemBytes > PAGE_BYTE_BUDGET) break;
+    bytes += itemBytes;
+    end++;
+  }
+
   return {
     __browserCliPage: true,
     items: items.slice(offset, end),
     offset,
-    limit,
+    limit: maxCount,
     total,
     nextOffset: end < total ? end : null,
   };