docs: add missing X-API-Key header to curl examples

[Perfect29]

The curl examples for /ask, /ask-llm, and /debug in the README
don't include the X-API-Key header, but all three endpoints require
it (via the verify_api_key dependency). Copying these examples as-is
returns a 401 "API key is missing" error.

The /debug example also had two issues:

• context=False? (trailing ?) which FastAPI can't parse as a
  boolean, causing a 422 error
• The code parameter contained a natural-language question instead of
  actual Python code

Changes:

• Added -H "X-API-Key: sugarai2024" to the /ask, /ask-llm, and
  /debug curl examples
• Fixed the /debug URL: context=false and used print('hello world') as a realistic code sample

Tested locally on macOS by running the original and fixed commands
against uvicorn main:app.

Before (all three return 401):

After (returns 200 with valid response):