Fix opencode-local adapter: parser, UI, CLI, and environment tests

- Move costUsd to top-level return field in parseOpenCodeJsonl (out of usage)
- Fix session-not-found regex to match "Session not found" pattern
- Use callID for toolUseId in UI stdout parser, add status/metadata header
- Fix CLI formatter: separate tool_call/tool_result lines, split step_finish
- Enable createIfMissing for cwd validation in environment tests
- Add empty OPENAI_API_KEY override detection
- Classify ProviderModelNotFoundError as warning during model discovery
- Make model discovery best-effort when no model is configured

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/adapters/opencode-local/src/server/execute.ts

@@ -340,7 +340,7 @@ export async function execute(ctx: AdapterExecutionContext): Promise<AdapterExec
       provider: parseModelProvider(modelId),
       model: modelId,
       billingType: "unknown",
-      costUsd: attempt.parsed.usage.costUsd,
+      costUsd: attempt.parsed.costUsd,
       resultJson: {
         stdout: attempt.proc.stdout,
         stderr: attempt.proc.stderr,