feat(settings): mark Claude CLI as coming soon, simplify provider form

[OmGuptaIND]

Summary

• Mark the Claude CLI row in Settings → Models → CLIs as Coming soon and make it non-interactive (Claude subscription support isn't ready yet).
• Rewrite the per-provider settings form (ProviderSettingsModal) with a far simpler, autosaving layout: single API-key input with inline arrow/check button, models as a clean list with hover-only × to remove, and an inline "+ add model" row. Removes the old "Save model changes" button.

Test plan

• Open Settings → Models → CLIs section, confirm the Claude row shows a dimmed "Coming soon" tag with no Connect/⋯ buttons and can't be clicked.
• Open Settings → Models → API keys, click any provider (e.g. OpenAI) and verify:
  • Compact header (icon + name + green dot when connected).
  • Paste a key and hit Enter → check icon briefly shows; key saves.
  • Models render as a list; hovering a row reveals × at the right; removing saves immediately.
  • Typing in "+ add model" and pressing Enter appends a row and saves immediately.
  • "Reset to defaults" link appears only when the current list differs from defaults.
• Open the Harness CLI setup modal and confirm its title bar and key input still look correct (shared styles preserved).

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