[BUG] Bedrock code-index embedder ignores the corporate proxy (ENOTFOUND), unlike the chat provider #1772

Describe the bug
The proxy fix from #905 only covers the Bedrock chat provider. The codebase-indexing embedder
builds its own BedrockRuntimeClient without a requestHandler, so behind a corporate proxy
Node resolves DNS locally and the call fails with ENOTFOUND — the same failure #905 fixed for
chat. getSystemProxyUrl is currently referenced from src/api/providers/bedrock.ts only.

To Reproduce
Steps to reproduce the behavior:

1. On a machine behind a corporate proxy (HTTPS_PROXY set, or VS Code http.proxy), configure
   the Amazon Bedrock provider — chat works, thanks to [BUG] Bedrock provider does not work behind a proxy #905.
2. In the codebase indexing settings, select bedrock as the embedder provider, same region
   and credentials.
3. Start indexing.
4. Embedding requests fail to reach AWS instead of being tunnelled through the proxy.

Expected behavior
The embedder resolves the proxy the same way the chat provider does, so both work behind a
corporate proxy.

Screenshots

Video

What version of zoo are you running
3.82.1

Additional context

• Chat path: src/api/providers/bedrock.ts calls getSystemProxyUrl(...) and, when a proxy is
  found, sets requestHandler: new NodeHttpHandler({ httpAgent, httpsAgent }).
• Embedder path: src/services/code-index/embedders/bedrock.ts creates
  new BedrockRuntimeClient({ userAgentAppId, region, credentials }) with no request handler.
• The fix looks like reusing the same few lines. A shared helper may be worth it: PR fix(bedrock): discover regional models and clarify inference routing #1719 adds
  a third Bedrock client for catalogue discovery, which wires the proxy again on its own.