Keep model catalog loads out of settings TUI repaints

[breedx]

Summary

• snapshot model configuration once per /model_settings session
• reuse the snapshot for names, descriptions, capability checks, defaults, and choices
• keep model-picker render and keypress paths free of config callbacks
• let model_supports_setting accept an optional preloaded catalog

Reproduction

The model picker called ModelFactory.load_config() 16 times per repaint: once in the list and 15 times while deriving capabilities for the details panel. For network-backed model catalogs, a 0.9s config load made each arrow/Enter/Esc repaint take 14.89s. The inner settings view remained responsive because it reused its supported-settings list.

Verification

• regression tests assert repeated picker repaints perform zero additional catalog loads
• internal TypeError propagation is covered (no exception-driven retry)
• focused model-settings suites: 131 passed on current upstream main
• Ruff and formatting clean