Initial commit: LLPSI tutoring slash commands

- Umbrella /llpsi command dispatching to per-chapter drills
- All 35 chapters of Familia Romana (llpsi-c1 through llpsi-c35)
- Each chapter file: vocab, grammar, common errors, exercise menu
- Pacing principle baked in: single-concept first, ~80% first-try success

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

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+.DS_Store
+*.swp
+*.swo
+.idea/
+.vscode/