fix: include response limit in build cache key

[Utkarshpandey0001]

Summary

• include the effective maxResponseBytes value in the build packaging identity
• prevent a shared artifact cache from reusing a wrapper with a stale response limit
• add regression coverage for distinct limits, same-limit cache reuse, and omitted-versus-explicit defaults

Testing

• confirmed the new regression failed before the fix because 1024-byte and 2048-byte limits produced the same build ID
• pnpm --filter @rivet-dev/dynamic-apps-core exec vitest run tests/build.test.ts
• pnpm build
• pnpm check-types
• pnpm check-boundaries
• pnpm lint
• full core test run: 9/10 passed; one existing agentOS-backed test exceeded its 5-second timeout under suite load, then passed alone in 3.8 seconds

The regression exercises buildAppRelease() with a shared artifact cache and verifies a 1536-byte response is rejected by a cached 1024-byte wrapper and accepted by the 2048-byte wrapper. This does not perform a real agentOS build-and-redeploy cycle.

Fixes #297

[the-company-company]

✅ No issues found

_{Reviewed commit ee306e5.}

[Utkarshpandey0001]

@NathanFlurry Hi, Could you please review this PR when you have a chance ? Let me know if you would like me to make any further changes. Thanks