Remove unused UDP discovery

[melvinfoo6776]

Summary

• remove the unused UDP discovery responder and its wildcard socket binding
• remove the obsolete discovery command-line options
• stop passing the obsolete --no-discovery launcher argument

Why

CodeQL reported py/bind-socket-all-network-interfaces because the dormant discovery responder bound UDP to 0.0.0.0. The macOS app already runs the bridge on 127.0.0.1 with discovery disabled, so deleting the unused network-facing feature is the smallest safe fix.

This addresses code-scanning alert #1.

Impact

The bridge remains loopback-only. Normal CodexBuddyMac behavior and its HTTP endpoints are unchanged.

Validation

• python3 -m py_compile CodexBuddyMac/CodexBuddyMac/Bridge/codex_usage_server.py
• python3 tests/test_claude_auth_recovery.py — 12 tests passed
• bash scripts/check-secrets.sh — passed
• ./scripts/security-check.sh — 15 passed, 0 failed, 0 warnings
• macOS Debug xcodebuild matching the CodeQL Swift build — succeeded