fix(lambda): bump PostOrder/PostLimitOrder memorySize 512→1024 MB (#658)

Both handlers iterate SUPPORTED_CHAINS at module load to build
StaticJsonRpcProvider + OrderValidator (+ V4 for PostOrder) maps. With
the V3 multi-chain rollout taking the list from ~4 to 18 chains, cold-
start blew past 512 MB:

  INIT_REPORT Init Duration: 3609.31 ms Phase: init Status: error
  Error Type: Runtime.OutOfMemory

Surfaced as 2-second axios timeouts from param-api → x-service. Other
handlers with the same pattern (check-order-status, get-orders) are
already at 1024 MB.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: codyborn

bin/stacks/lambda-stack.ts

@@ -221,7 +221,9 @@ export class LambdaStack extends cdk.NestedStack {
       entry: path.join(__dirname, '../../lib/handlers/post-order/index.ts'),
       handler: 'postOrderHandler',
       timeout: Duration.seconds(29),
-      memorySize: 512,
+      // Module-load builds StaticJsonRpcProvider + OrderValidator (+ V4) maps
+      // for every SUPPORTED_CHAIN; 512 MB OOMs at cold-start past ~16 chains.
+      memorySize: 1024,
       bundling: {
         minify: true,
         sourceMap: true,
@@ -237,7 +239,9 @@ export class LambdaStack extends cdk.NestedStack {
       entry: path.join(__dirname, '../../lib/handlers/post-limit-order/index.ts'),
       handler: 'postLimitOrderHandler',
       timeout: Duration.seconds(29),
-      memorySize: 512,
+      // Same per-chain map construction as PostOrder above — bumped to avoid
+      // cold-start OOM as the supported-chain list grew.
+      memorySize: 1024,
       bundling: {
         minify: true,
         sourceMap: true,