Fix GitHub workflow: .env.llm-tests lost on checkout (#1041)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: thomasnordquist <7721625+thomasnordquist@users.noreply.github.com>
Co-authored-by: Thomas Nordquist <thomasnordquist@users.noreply.github.com>

.env.example

@@ -0,0 +1,18 @@
+# Example .env file for LLM tests
+# Copy this to .env.llm-tests and fill in your API key
+
+# Option 1: OpenAI (recommended for development)
+export OPENAI_API_KEY=sk-your-openai-api-key-here
+
+# Option 2: Google Gemini
+# export GEMINI_API_KEY=your-gemini-api-key-here
+
+# Option 3: Generic LLM API (specify provider)
+# export LLM_API_KEY=your-api-key-here
+# export LLM_PROVIDER=openai  # or 'gemini'
+
+# Enable LLM tests (required)
+export RUN_LLM_TESTS=true
+
+# Optional: Token limit for neighboring topics (default: 500)
+# export LLM_NEIGHBORING_TOPICS_TOKEN_LIMIT=500