feat(foundry): memory investigation tooling and VFS pool spec

Add memory monitoring instrumentation, investigation findings, and
SQLite VFS pool design spec for addressing WASM SQLite memory spikes.

- Add /debug/memory endpoint and periodic memory logging (dev only)
- Add mem-monitor.sh script for continuous memory profiling with
  automatic heap snapshot capture on spike detection
- Add configureRunnerPool to registry setup for engine driver support
- Document memory investigation findings (per-actor cost, spike behavior)
- Write SQLite VFS pool spec for bin-packing actors onto shared WASM instances
- Add foundry-mem-monitor and foundry-dev-engine justfile recipes
- Add compose.dev.yaml engine driver and platform support

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

examples/e2b/src/index.ts

@@ -7,7 +7,6 @@ if (process.env.ANTHROPIC_API_KEY) envs.ANTHROPIC_API_KEY = process.env.ANTHROPI
 if (process.env.OPENAI_API_KEY) envs.OPENAI_API_KEY = process.env.OPENAI_API_KEY;
 
 const client = await SandboxAgent.start({
-  // ✨ NEW ✨
   sandbox: e2b({ create: { envs } }),
 });