feat(TASK-041): add WireApi enum and wire-aware Responses dispatch

Introduce a WireApi enum (responses|chat) with an optional wire_api
config field on the openai and openai-compatible clients, resolved
through a single resolve_wire_api fn: codex forces the responses wire
(an explicit wire_api: chat there is a hard config error), an explicit
wire_api wins everywhere else, and the default stays chat for now.
The openai dispatch generalizes from (RequestData, bool) to
(RequestData, WireApi), and the openai-compatible client gains opt-in
Responses dispatch (URL, body, extractor, and streaming forks).

Both patch layers are now wire-aware: RequestData carries its wire,
RequestPatch gains a responses section, and patch_request_data selects
patches per wire. This deliberately FIXES a codex bug: chat-shaped
model patches (e.g. o3-high's max_tokens/temperature/top_p/
reasoning_effort tweaks) previously merged wire-blind into codex
responses bodies, poisoning them with chat-only keys. On the responses
wire only an explicit responses sub-patch applies; chat-wire patching
is byte-identical to before (pinned by a regression test).

src/client/bedrock.rs

@@ -73,6 +73,7 @@ impl BedrockClient {
             url: _,
             headers,
             body,
+            ..
         } = request_data;
 
         let builder = aws_fetch(
@@ -126,6 +127,7 @@ impl BedrockClient {
             url: _,
             headers,
             body,
+            ..
         } = request_data;
 
         let builder = aws_fetch(