feat: add tested local chat proxy

[OgeonX-Ai]

Summary

• add an OpenAI-compatible local chat completions proxy endpoint
• record proxied prompts and execution outcomes in EventStore
• enforce JSON requests and loopback-only upstreams unless allowNonLoopback is enabled
• redact failure artifacts in proxy execution records
• add isolated route tests for success, validation, upstream failure, network failure, and route failure paths

Verification

• git diff --check
• npm.cmd run test:coverage
• npm.cmd run release:verify

Coverage: 53 test files, 393 tests, 100% statements/branches/functions/lines.

[chatgpt-codex-connector]

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