docs: add Ollama launch integration documentation (#716)

Document the new `ollama launch openclaude` command as a shortcut
for running OpenClaude through a local Ollama instance. This is
now supported in Ollama's launch system and handles all environment
variable setup automatically — no manual env vars needed.

Changes:
- README.md: Add "Using Ollama's launch command" section after the
  manual Ollama env var setup, and update the provider table to
  list `ollama launch` as a setup path for Ollama
- docs/advanced-setup.md: Add `ollama launch` as the recommended
  method at the top of the Ollama section, with the manual env var
  approach kept below as an alternative

docs/advanced-setup.md

@@ -84,6 +84,16 @@ OpenRouter model availability changes over time. If a model stops working, try a
 
 ### Ollama
 
+Using `ollama launch` (recommended if you have Ollama installed):
+
+```bash
+ollama launch openclaude --model llama3.3:70b
+```
+
+This handles all environment setup automatically — no env vars needed. Works with any local or cloud model available in your Ollama instance.
+
+Using environment variables manually:
+
 ```bash
 ollama pull llama3.3:70b