## Why
Local MCP requests can fail when the platform TLS backend cannot negotiate a
protocol version with an HTTPS endpoint.
## What changed
- Retry replayable local MCP requests once with rustls after a recognized TLS
protocol-version negotiation failure. Keep certificate, timeout, and unrelated
connection failures on the existing error path.
- Remember successful fallback per HTTPS origin and outbound route, while keeping
the platform TLS backend as the default for other destinations.
- Share the fallback-enabled client across local MCP resolution, CLI login, and
OAuth discovery while preserving remote environment HTTP clients.
## Testing
Added coverage for platform-specific error detection, request replay, cached
fallback reuse and isolation, non-replayable requests, redirects, and remote MCP
client selection.
GitOrigin-RevId: 39a2d96fdb2ea0e51df14f652ba2a953d24e69a1
## What changed
- Rename `ReqwestHttpClient` to `RouteAwareHttpClient` to reflect that delegated HTTP uses Codex's shared route-aware transport.
- Use `codex_http_client` response and error types plus transport-neutral `http` and `url` types, removing the exec server's direct `reqwest` dependency.
## Testing
- Cover fragment stripping and Unicode hostname normalization for delegated HTTP requests.
GitOrigin-RevId: 8b0fc60a76004feb57198bfb4afb1371c9ceb1bd
Celia Chen