feat: add unrestricted network mode

[richardkiene]

Summary

• add trusted-user network.mode: "unrestricted" for open outbound internet access while retaining Sandlot's filesystem, process, environment, credential, socket, local-binding, and lifecycle protections
• keep existing configurations in strict filtered mode by default and reject ambiguous project/sibling network rules
• validate the effective mode across the isolated Sandbox Runtime boundary and serialize initialization/reset ownership to prevent stale unrestricted state
• add redaction-safe diagnostics, macOS enforcement coverage, and self-contained public documentation
• keep SPEC.md local-only by removing it from Git/package output and ignoring future local copies

Configuration

{
  "network": {
    "mode": "unrestricted"
  }
}

Only trusted user policy may select this mode. Any sandbox-readable data can then be sent to arbitrary internet destinations.

Verification

• npm run release:verify
  • 573 unit/contract tests passed
  • 24 macOS integration tests passed; 1 Linux-only test skipped
  • 21 installed-package smoke tests passed; 1 platform test skipped
  • typecheck, build, and pack checks passed
• npm ls --all
• git diff --check
• independent whole-branch security review: PASS

Linux/Bubblewrap remains intentionally deferred for the first release.