Expose local model controls in desktop Settings

## Problem

Desktop users need explicit, understandable control over optional installation, enablement, updates and removal.

## Proposed change

Extend `qt_adapter.py` and `qml/SettingsView.qml` through #460 state/commands. Show availability, approximate size, progress, enabled/disabled state, retry/reinstall, incompatibility/update state and removal. Communicate that inference runs locally and draft data is not sent to an AI service. QML remains presentation-only; no file/network/runtime logic. Include required deployment-list entries for changed QML. Recommendation dialogue is Display progressive recommendation dialogue on desktop.

## Acceptance Criteria

- [ ] AC1: An actual desktop Settings journey exercises not-installed, downloading, installed-disabled, enabled and recoverable-error states with appropriate available controls.
- [ ] AC2: A desktop opt-in check shows size and privacy information before download and starts no transfer without explicit user action.
- [ ] AC3: A restart/disable/remove journey preserves disabled installations, reflects persisted choices, and removes the model without breaking normal application use.
- [ ] AC4: An incompatible/update-available journey offers deliberate recovery/update and never silently transfers a new artifact.
- [ ] AC5: Actual narrow/wide-window and keyboard/accessibility checks show usable controls while download/runtime work remains off the UI thread.

## Implementation classification

- **Estimated size:** M
- **Orchestration risk:** High
- **Reason:** The adapter must faithfully expose asynchronous lifecycle and error states without owning them.

## Dependencies

Direct prerequisites: #460. Documentation consumer: Document local narration installation and troubleshooting.

Start with prerequisite #460 to understand the state and commands, then inspect qt_adapter.py and qml/SettingsView.qml. Verify the five installation states, explicit opt-in and privacy messaging, persisted disable/remove behavior, deliberate recovery, and usable narrow/wide-window and keyboard controls while QML remains presentation-only.

Scritto dal modello di indicizzazione a partire dal testo della issue.