Pi v0.80.8 unifies runtime, adds Grok 4.5

Centralizing model runtimes and authentication simplifies the developer experience at the cost of breaking existing session configurations, showing that the project is prioritizing rapid architecture iteration over API stability.

• –The new unified ModelRuntime removes boilerplate by handling provider-owned login discovery, ambient auth status, and dynamic catalogs directly.
• –Background catalog refreshing throttled to four hours keeps model listings fresh without degrading terminal startup performance.
• –Adding Grok 4.5 support ensures that Pi remains a competitive playground for testing state-of-the-art LLMs on the command line.
• –Deprecating exported storage backends in favor of pi-ai CredentialStore enforces cleaner encapsulation but forces immediate code updates.