fix(proxy): add OpenAI-compatible model discovery

[Gout999]

Addresses #1098.

Summary

• Add OpenAI-compatible GET /models and GET /v1/models endpoints.
• Add the same model-listing paths under /<agent>/<spaceId>/, which covers Hermes custom-provider probes such as /hermes/default/models.
• Expose the configured public modelName alias when present, fall back to the configured model ID, and return an empty list when no pricing table is configured.
• Document the endpoint in both MemoryProxy READMEs.

Validation

• npm exec vitest run src/__tests__/server-models.test.ts — 2 passed.
• git diff --check — passed.
• The package-wide npm run typecheck still reports existing errors in unrelated files (anthropicHandler.ts, codexHandler.ts, config.ts, and the cost-guard alias); it is not reported as a pass here.

[Maxwell-Code07]

Thank you so much for your attention and contribution! We will arrange an internal review for this PR shortly, and all feedback will be shared right here in the discussion.