[dgsienko]

Fixes from a full-repo slop audit, Python and docs half. Every finding was re-checked against the code before it was fixed.

• Dead code: the delete_bg/delete_hover theme fields (equal to remove_* in all 16 themes), get_git_user_name, reload_branch_name, the write-only current_view, the unused view_mode setting, and the unused dim parameter on the TUI's style()
• The active theme is derived from theme_index, not a second module global. Settings are built in one AppState.settings() and not three times.
• Word highlights use one toggle block and drop guards for input html.escape can't produce
• Function-local imports are hoisted where nothing needs them local
• README: kroki gets every diagram language, not only mermaid and plantuml, and .diffuiignore only applies to changed-scope search. AGENTS.md drops sections that restated the README.

Behavior changes: none a user would see. view_mode disappears from /api/settings, and nothing read it. Theme switching through the settings API gets a feature test, since the old one tested the deleted global.

Version 0.11.1.