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/parse.test.ts

@@ -37,8 +37,8 @@ describe("parseOpenCodeJsonl", () => {
       inputTokens: 120,
       cachedInputTokens: 20,
       outputTokens: 50,
-      costUsd: 0.0025,
     });
+    expect(parsed.costUsd).toBeCloseTo(0.0025, 6);
     expect(parsed.errorMessage).toContain("model unavailable");
   });