feat: Migrate to ultrathin monolith architecture

Consolidate 3 separate applications (reports-app, data-entry-app, telegram-bot) into a unified
architecture with single backend and frontend:

Backend Changes:
- Unified FastAPI backend at backend/ with modular structure
- Modules: reports, data_entry, telegram in backend/modules/
- Centralized config.py and main.py with all routers registered
- Single worker mode (--workers 1) for Telegram bot compatibility
- Shared Oracle connection pool and JWT authentication
- Unified requirements.txt and environment configuration

Frontend Changes:
- Single Vue.js SPA with module-based routing
- Unified frontend at src/ with modules in src/modules/{reports,data-entry}/
- Shared components and stores in src/shared/
- Error boundaries for module isolation
- Dual API proxy in Vite for module communication

Infrastructure:
- New unified startup scripts: start-prod.sh, start-test.sh, start-backend.sh
- Environment templates: .env.dev.example, .env.test.example, .env.prod.example
- Updated deployment scripts for Windows IIS
- Simplified SSH tunnel management

Documentation:
- Comprehensive CLAUDE.md with architecture overview
- Module-specific docs in docs/{data-entry,telegram}/
- Architecture decision records in docs/ARCHITECTURE-DECISIONS.md
- Deployment guides consolidated in deployment/windows/docs/

This migration reduces complexity, improves maintainability, and enables easier
deployment while maintaining all existing functionality.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/data/README.md

@@ -0,0 +1,45 @@
+# Backend Runtime Data
+
+This directory contains runtime data generated by the unified backend.
+
+## Directory Structure
+
+```
+data/
+├── cache/              # Reports module cache (hybrid L1+L2)
+│   └── *.db           # SQLite L2 cache database
+├── receipts/          # Data Entry module data
+│   ├── *.db          # SQLite receipts database
+│   └── uploads/      # User-uploaded files (receipts, attachments)
+└── telegram/         # Telegram bot data
+    └── *.db          # SQLite bot auth/session database
+```
+
+## Git Behavior
+
+- **Ignored**: All `*.db` files and `uploads/` contents
+- **Committed**: Only `.gitkeep` files to preserve directory structure
+
+## Environment-Specific Databases
+
+Different environments use separate databases:
+
+- **Development** (`.env.prod`):
+  - Cache: `roa2web_cache.db`
+  - Receipts: `receipts_dev.db`
+  - Telegram: `telegram.db`
+
+- **Test** (`.env.test`):
+  - Cache: `roa2web_cache_test.db`
+  - Receipts: `receipts_test.db`
+  - Telegram: `telegram_test.db`
+
+- **Production** (`.env.prod`):
+  - Cache: `roa2web_cache_prod.db`
+  - Receipts: `receipts_prod.db`
+  - Telegram: `telegram_prod.db`
+
+## Auto-Created
+
+All databases and directories are created automatically on first run.
+No manual setup required.