## Why
Remote plugin requests did not use Codex's effective outbound proxy policy, so
they could bypass configured system proxy and PAC routing.
## What changed
- Route remote plugin catalog, mutation, sharing, upload, and bundle download
requests through the configured route-aware HTTP client.
- Select routes using the complete request URL, including encoded query
parameters and backend-provided signed upload or download URLs.
- Preserve standard Codex headers and suppress diagnostics for URLs or headers
that may contain credentials.
## Testing
Add coverage for route selection of catalog queries, workspace plugin uploads,
and backend-provided bundle download URLs.
GitOrigin-RevId: 106936659e21decf145b6ab4d4be84992e386861
## Why
The curated plugin startup sync can fall back from Git to HTTP, but those
requests did not use Codex's effective outbound proxy policy.
## What changed
- Thread the configured HTTP client factory into curated plugin sync.
- Route GitHub API, zipball, backup metadata, and returned download URLs
through the route-aware client when system proxy support is enabled.
- Preserve the existing default HTTP client behavior, including its custom CA
fallback, when system proxy support is disabled.
- Apply the standard Codex headers to startup-sync HTTP requests.
## Testing
Add coverage that records route selection for repository, archive, metadata,
and backend-supplied download URLs, and verifies standard headers are sent.
GitOrigin-RevId: e1ea13bdab58a84c9948a2c8b82a5ec5c964ea99
