refactor: Dead code cleanup and automate scripts consolidation

## Changes

### Backend Cleanup
- Delete 10 root-level JS debug/test files
- Delete 19 scripts (old generators, one-off utilities)
- Delete src/scripts/ directory entirely (6 one-time scripts)
- Remove 4 dead package.json script references
- Delete 47-file Python lessons backup directory

### Frontend Cleanup
- Delete 3 unused UI components (input, table, stat-card)
- Delete unused notes.ts service and useSlidingPages hook
- Delete lessonHistoryStore stub and its test
- Delete entire stories/ directory (26 Storybook templates)
- Delete 4 Java visualizer files (JavaMessagesView, DeviceCard, RemoteControl, examples)
- Delete playwright-report/ and add to .gitignore

### Root Level Cleanup
- Delete 10 root test/analysis scripts (test-*.mjs, *.py)
- Delete 17 non-Render deploy files (Fly.io, Railway, Docker)
- Delete 5 misc files (android plan, setup docs, shell scripts)
- Consolidate 3 language-specific automation guides into 1 unified guide

### Script Refactoring (Phase 4)
- Create scripts/lib/lesson-automation.ts with shared logic
- Reduce each automate-*-lessons.ts from 400+ lines to 50-90 lines
- Each script now only defines language-specific config and calls runWithCleanup()
- All 4 languages (Python, C, JavaScript, Java) use same pipeline

### Verification
- Backend build: PASS
- Frontend build: PASS
- No stale import references found

Total: ~105 files deleted, 4 scripts refactored, 1 new shared library

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: jammy0903

.claude/LESSON_AUTOMATION_GUIDE.md

@@ -0,0 +1,139 @@
+# Lesson Automation Guide (All Languages)
+
+**Purpose**: YAML -> JSON -> DB lesson automation for all supported languages
+
+---
+
+## Overview
+
+All languages follow the same automation pipeline:
+
+```
+YAML Template -> Simulator Execution -> JSON Generation -> DB Import
+```
+
+**Pipeline**: `pnpm run automate:<language>`
+
+---
+
+## Directory Structure
+
+```
+packages/backend/
+├── lesson-templates/<language>/    # YAML templates
+│   ├── <lang>-1-1.yaml
+│   └── ...
+├── scripts/
+│   ├── automate-python-lessons.ts
+│   ├── automate-c-lessons.ts
+│   ├── automate-js-lessons.ts
+│   ├── automate-java-lessons.ts
+│   └── lib/lesson-automation.ts    # Shared automation logic
+└── prisma/content/<language>/lessons/  # Generated JSON
+    ├── <lang>-1-1.json
+    └── ...
+```
+
+---
+
+## YAML Template Structure
+
+All languages use the same YAML schema:
+
+```yaml
+lessonId: "<lang>-<chapter>-<lesson>"
+title: "Lesson Title"
+concept: "Core concept explanation"
+
+code: |
+  # Language-specific code here
+
+annotations:
+  - line: 1
+    title: "Step title"
+    explanation: |
+      Markdown explanation of this line
+
+quiz:
+  question: "Quiz question?"
+  options: ["A", "B", "C", "D"]
+  correctIndex: 0
+  explanation: "Why this answer is correct"
+
+misconceptions:
+  - wrong: "Common misconception"
+    correct: "Correct understanding"
+    why: "Explanation"
+
+keyTakeaway: "One-line summary"
+```
+
+---
+
+## Language-Specific Differences
+
+| Language | Simulator | Memory State Key | Visualization Type | Lesson ID Prefix |
+|----------|-----------|------------------|--------------------|-----------------|
+| Python | PythonSimulationService | pythonMemoryState | pythonMemory | py- |
+| C | CSimulationService | cMemoryState | cMemory | c- |
+| JavaScript | JsSimulationService | jsMemoryState | jsMemory | js- |
+| Java | JavaSimulationService | javaMemoryState | javaMemory | java- |
+
+### Chapter ID Parsing
+
+- **Python**: `py-1-1` -> chapter 1
+- **C**: `c-1-1` -> chapter 1
+- **JavaScript**: `js-1-1` -> chapter 1
+- **Java**: `java-1-1` -> chapter 1
+
+---
+
+## Running Automation
+
+```bash
+cd packages/backend
+
+# Run for specific language
+pnpm run automate:python
+pnpm run automate:c
+pnpm run automate:js
+pnpm run automate:java
+```
+
+### Expected Output
+
+```
+Step 1: Find YAML files
+Step 2: YAML -> JSON conversion (runs simulator)
+Step 3: JSON -> DB import
+Final stats: N files processed, M succeeded, K failed
+```
+
+---
+
+## Troubleshooting
+
+### "Lesson not found in DB" (skipped)
+
+Lesson metadata doesn't exist in DB. Create the lesson entry first via Prisma.
+
+### Simulation failed
+
+1. Check simulator service for the language
+2. Verify compiler/runtime is installed (GCC for C, JDK for Java, etc.)
+3. Check code syntax in YAML template
+
+### Type mismatch
+
+Ensure `visualizationType` and memory state keys match the language config.
+
+---
+
+## Checklist for Adding a New Language
+
+1. Create `lesson-templates/<language>/` directory
+2. Write YAML templates following the schema above
+3. Create `automate-<language>-lessons.ts` (or add config to shared lib)
+4. Add `automate:<language>` script to `package.json`
+5. Run and verify: `pnpm run automate:<language>`
+6. Check browser: lessons appear in course page