Remove frontend JSON export actions
- Remove user-visible JSON export options from report editor, report management, template management, bulk template export, and AI debug logs.
- Keep HTML template package and PDF/browser print exports as the supported frontend export formats.
- Change per-template export to generate reusable HTML template packages.
- Preserve legacy JSON template import compatibility without exposing new JSON export buttons.
- Update README, AGENTS, feature, requirement, design, module, API contract, progress, and testing docs for the export policy change.