What changed

• Replaced the template Items model, API, tests, navigation, and frontend with Lessons.
• Added target-language choices for Spanish and French, native-language selection for English, and a free-form lesson goal prompt.
• Added lesson creation, listing, and deletion in the frontend.
• Added an Alembic migration and regenerated the typed frontend API client.
• Added sanitized .env.example files while keeping real .env files ignored.
• Added a root .dockerignore so local dependencies and secrets are excluded from Docker build contexts.

Why

This establishes the first usable slice of the language-learning application. Users can describe what they want to practice and save a language lesson, leaving AI-generated lesson-plan content for a later change.

Developer impact

The migration replaces the template item table with lesson. Existing template item rows are deleted because they cannot be meaningfully mapped to language and prompt fields. Developers should copy the example environment files to local .env files before starting Compose.

Validation

• Staged content audited for generated local secrets, private keys, and common token formats
• Real root and frontend .env files confirmed ignored and excluded from the commit
• TypeScript type-check passed
• Ruff passed
• Mypy passed
• Alembic reports the new migration as the single head
• Docker Compose configuration interpolation passed
• Application verified through Docker Compose