Phase 5.11: Configure native Spellcheck without autocorrect

[danielmrdev]

What to build

Add a persisted native Spellcheck Preference without authorizing automatic changes. A writer can enable or disable non-mutating spelling indications and use native suggestions inside the Writing surface.

Acceptance criteria

• General Settings exposes a default-on Spellcheck Preference that applies live and persists.
• WritingSurface uses the native spelling service and preserves its native suggestion, cut, copy, paste, and select-all context menu.
• Browser context menus remain disabled outside WritingSurface.
• Autocorrect, autocapitalization, smart punctuation, and every other automatic content mutation remain disabled regardless of Spellcheck state.
• The operating system, not the interface locale, controls dictionaries and suggestion language.
• Component and Linux smoke checks cover both states without weakening plain-text paste or editor behavior.

Blocked by

• Phase 5.9: Switch the interface between English and Spanish #45

Workspace

• Mode: parallel lane
• Branch: feat/tauri-2-replatform-47
• Worktree: /home/daniel/Projects/lettera/.worktrees/feat-tauri-2-replatform-47
• Integrates into: feat/tauri-2-replatform
• Remote policy: local only — never push
• Completion: when unblocked, create the lane from the latest integration commit; validate it, merge it locally into integration with approval, validate integration, remove the lane worktree, and delete the local lane branch

[danielmrdev]

Frozen by the approved UI stack decision gate in #49. Do not implement this direct-migration ticket while the Floem/Tauri bake-off is open. Native dependency #54 records the live gate. After the blind decision, this ticket will be reviewed and respecified only if Tauri wins; if Floem wins, it will be closed as replaced.