fix(test): mock $env/dynamic/private in llm-logging spec

Tests passed locally because .env provided OPENAI_BASE_URL and
OPENAI_API_KEY. In the Docker build stage there is no .env, so
createLLM() threw 'OPENAI_BASE_URL environment variable is not set'
before the mocked OpenAI client ever ran, causing 3 test failures.

Add vi.mock('$env/dynamic/private', ...) with stub values so the
tests are self-contained and environment-independent.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/tests/llm-logging.spec.ts

@@ -13,6 +13,16 @@ vi.mock('openai', () => ({
 	}
 }));
 
+// Mock env so tests pass in environments without .env (e.g. Docker CI builds)
+vi.mock('$env/dynamic/private', () => ({
+	env: {
+		OPENAI_BASE_URL: 'http://localhost:11434/v1',
+		OPENAI_API_KEY: 'test-key',
+		LLM_MODEL: 'test-model',
+		LLM_REQUEST_TIMEOUT_MS: undefined
+	}
+}));
+
 // Import AFTER mocking
 import { checkLLMHealth, checkModelAvailability } from '$lib/server/llm';