fix(providers): scope codex effort defaults and options to per-model capability

[astyfx]

Summary

• GPT-5.6's per-model reasoning-effort scale (Sol/Terra up to ultra, Luna up to max, GPT-5.5 up to xhigh) wasn't reflected anywhere in the UI or default-resolution logic; effort pickers offered the full scale regardless of the selected model.
• Adds a dynamic (App Server model/list) + static per-model effort registry so:
  • the default Codex effort prefers Codex's own recommendation, falling back to medium only when unknown
  • every effort selector (preset editor, chat-input cycle, settings default, providers-section reasoning help) is scoped to what the active model actually accepts, clamping to the nearest supported value on model switch
• Adds the missing max/ultra entries to the providers-section reasoning help list (previously stopped at xhigh)
• Merges the App Server's model/list catalog with the static GPT-5.6 catalog so newer models stay selectable even against an older installed Codex binary
• Fixes the preset-edit popover in PresetBar closing itself immediately due to Radix's default focus-return stealing focus from the freshly opened editor

Key changes

• src/lib/providers/model-catalog.ts: supportedCodexReasoningEfforts capability field, dynamic default/supported-effort registries, listCodexReasoningEffortsForModel, clampCodexEffortToModel
• src/lib/providers/use-codex-model-catalog.ts: registers dynamic default/supported efforts from the live catalog fetch; merges dynamic + static model lists
• src/lib/providers/runtime-option-contract.ts: listCodexEffortOptionsForModel helper
• src/lib/task-presets.ts, src/components/layout/task-preset-editor.tsx: model-scoped effort options in the preset editor
• src/components/session/chat-input.runtime.ts, ChatInput.tsx: model-scoped effort cycling + clamp on model switch
• src/components/layout/settings-dialog-sections.tsx, settings-dialog-providers-section.tsx: model-scoped default-effort selector; added max/ultra to the reasoning help list
• src/components/layout/PresetBar.tsx: onCloseAutoFocus fix for the edit popover
• src/store/app.store.ts: default codexReasoningEffort updated to xhigh (verified server default for the default model)

Test plan

• bun run typecheck
• Focused tests: model-catalog, codex-model-catalog-merge (new), codex-runtime-options, task-presets, provider-runtime-options, ipc-schemas, chat-input.runtime, model-selector-utils, model-shortcuts, provider-mode-presets — 107 pass / 0 fail
• Manual: open the preset bar, click "Edit…" on a preset and confirm the popover stays open; switch a Codex preset/chat model to GPT-5.6 Luna and confirm "Ultra" is not offered