feat: improve model filling and overlay restore in model picker

[Paulkm2006]

Summary

• Add fill all option when setting model for Claude Code
• Fix overlay restore for model fetch picker

Changes

• Added tui_key_fill_all() i18n function (中文: "填充全部", English: "fill all") in src-tauri/src/cli/i18n.rs
• Added a key handler in src-tauri/src/cli/tui/app/overlay_handlers/pickers.rs , in ClaudeModelPicker select mode, pressing a copies the currently selected field's value to all 5 model fields
• Updated the key bar in src-tauri/src/cli/tui/ui/overlay/pickers.rs to display the a key hint
• In handle_model_fetch_picker_key Enter handler (src-tauri/src/cli/tui/app/overlay_handlers/pickers.rs), when the field is ClaudeModelConfig, the overlay now restores to Overlay::ClaudeModelPicker instead of Overlay::None
• Similarly, the Esc key (src-tauri/src/cli/tui/app/overlay_handlers/pickers.rs) also returns to ClaudeModelPicker when the source was the Claude model picker

Tests

Tested locally