Revert OpenCode dual-export — Phoenix only

The OpenLIT secondary exporter regressed tool-call parsing in OpenCode:
OpenLIT's image doesn't currently host an OTLP receiver on 4328, so the
exporter retries failed silently and the failures cascaded into the AI
SDK's telemetry pipeline. Symptom: model output came through as raw
Qwen3-Coder XML tool-call text instead of being parsed into actual tool
invocations.

Re-add when openlit.yml gets an otel-collector sidecar that actually
listens on the receiver ports.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

opencode/README.md

@@ -75,17 +75,18 @@ The plugin uses `@opentelemetry/exporter-trace-otlp-proto` (not `-http`)
 because Phoenix's OTLP receiver only speaks protobuf — the JSON variant
 returns 415.
 
-Spans are dual-exported: Phoenix (per-trace waterfall) and OpenLIT (fleet
-metrics). Each destination has its own batch processor so a hiccup at
-one doesn't block the other.
+Spans go to Phoenix only. Earlier versions of this plugin dual-exported
+to OpenLIT as well, but OpenLIT's container doesn't currently host an
+OTLP receiver — the failing exporter cascaded into OpenCode's tool-call
+parsing pipeline and broke tool use. Re-enable once `openlit.yml` adds
+an `otel-collector` sidecar.
 
 Defaults can be overridden via env vars (set before launching opencode):
 
 | Variable | Default | Purpose |
 |---|---|---|
 | `PHOENIX_OTLP_ENDPOINT` | `http://framework:6006/v1/traces` | Phoenix HTTP target |
-| `OPENLIT_OTLP_ENDPOINT` | `http://framework:4328/v1/traces` | OpenLIT HTTP target. Set to `off` to disable. |
-| `PHOENIX_SERVICE_NAME` | `opencode` | Service / project name (both backends) |
+| `PHOENIX_SERVICE_NAME` | `opencode` | Phoenix project name |
 | `PHOENIX_OTEL_DEBUG` | unset | `1` to surface OTel internal logs |
 
 ### Verifying