fix(proxy): disable audit buffer for standalone nono proxy

[panga]

Linked Issue

Closes #1501

Summary

nono proxy (standalone mode) logs audit buffer full on every request once the
4096-event ring buffer fills. The buffer exists only for rollback audit recording; the
standalone path has no rollback consumer and no code that drains it.

PR #1682 introduced enable_network_audit / --no-audit to disable the buffer on the
nono run path, but its description explicitly noted standalone nono proxy was left
unchanged. A 30-second periodic drain loop was added as a workaround in
proxy_command.rs, but in any burst-traffic window the buffer still fills and the
warning fires within that window.

Fix: set proxy_config.enable_network_audit = false in run_proxy alongside the
other standalone-specific overrides (bind_addr, require_auth, max_connections,
etc.). Remove the drain loop, which existed solely to compensate for the missing flag.

Agent Disclosure (if applicable)

This PR is generated by an AI agent (Claude). Files consulted:
crates/nono-cli/src/proxy_command.rs, crates/nono-proxy/src/config.rs,
crates/nono-proxy/src/server.rs, crates/nono-cli/src/launch_runtime.rs.

The change is scoped to the standalone nono proxy command path and does not affect
sandboxed nono run/nono shell/nono wrap flows. Confirmed compliance with
repository coding and security requirements: no unwrap/expect, uses existing
NonoError, no path handling involved.

Test Plan

# Build
make build-cli

# Existing tests pass
make test-cli

# Manual: drive high request volume through standalone proxy, confirm no warnings
nono proxy &
for i in $(seq 1 200); do
  curl -s -x http://localhost:<port> http://example.com -o /dev/null
done
# Expect: no "WARN nono_proxy::server: audit buffer full" lines in output

Checklist

• An issue exists and is linked above
• All commits are signed-off, using DCO
• All new code follows the project's coding standards (CLAUDE.md) and is covered by tests
• Public-facing changes are paired with documentation updates
• If this PR introduces a major feature, capability, or security-relevant change, a corresponding NEP has been opened or accepted and is linked

[github-actions]

PR Review Summary

Size

Metric	Value
Lines added	+7
Lines removed	-22
Total changed	29
Classification	Small (< 50 lines)

Affected crates

• crates/nono-cli — CLI changes. Verify argument parsing, flag documentation, and UX behaviour across supported platforms.

Blast radius — Contained

This PR touches: source code

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_{Updated automatically on each push to this PR.}

[nogent-nolabs-ai]

nogent code review

No blocking issues; 0 findings.

Findings: none flagged in scope.

_{Automated code + security review. CI already covers clippy, rustfmt, tests, cargo-audit and commit-lint.}

[SequeI]

lgtm! I need to get into the habit of remembering standalone proxy now exists..