Revert CLAUDE_API_KEY to ANTHROPIC_API_KEY throughout the repository

Reverted all instances of CLAUDE_API_KEY back to ANTHROPIC_API_KEY to maintain
compatibility with existing infrastructure and GitHub secrets. This affects:
- Environment variable examples (.env.example files)
- Python scripts and notebooks
- Documentation and README files
- Evaluation scripts and test files

Other naming changes (Claude API, Claude Console, Claude Docs, Claude Cookbook) remain intact.

🤖 Generated with Claude Code

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

skills/text_to_sql/evaluation/README.md

@@ -20,7 +20,7 @@ See the official docs [here](https://www.promptfoo.dev/docs/getting-started)
 
 ### Getting Started
 
-To get started, set your CLAUDE_API_KEY environment variable, or other required keys for the providers you selected. You can do `export CLAUDE_API_KEY=YOUR_API_KEY`.
+To get started, set your ANTHROPIC_API_KEY environment variable, or other required keys for the providers you selected. You can do `export ANTHROPIC_API_KEY=YOUR_API_KEY`.
 
 Then, `cd` into the `evaluation` directory and write `npx promptfoo@latest eval -c promptfooconfig.yaml --output ../data/results.csv`
 

skills/text_to_sql/guide.ipynb

@@ -101,7 +101,7 @@
     "from IPython.display import display\n",
     "\n",
     "# Set your Claude API key\n",
-    "os.environ[\"CLAUDE_API_KEY\"] = \"YOUR_CLAUDE_API_KEY\"\n",
+    "os.environ[\"ANTHROPIC_API_KEY\"] = \"YOUR_ANTHROPIC_API_KEY\"\n",
     "os.environ[\"VOYAGE_API_KEY\"] = \"YOUR_VOYAGE_API_KEY\"\n",
     "\n",
     "# Initialize the Anthropic client\n",