Add configuration template files (.env.example, .dockerignore)

Added essential configuration templates that were missing from the
repository due to overly restrictive .gitignore patterns.

Changes to .gitignore:
- Added negation patterns for .env.example files
- Added negation patterns for .dockerignore files
- These are safe template files with placeholder values

Files added:
- .env.example (root): Main environment configuration template
- reports-app/backend/.env.example: Backend configuration template
- reports-app/frontend/.env.example: Frontend configuration template
- reports-app/telegram-bot/.env.example: Telegram bot config template
- reports-app/telegram-bot/.dockerignore: Docker build exclusions

These template files help developers quickly set up their local
development environment by copying and customizing them.

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

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

reports-app/frontend/.env.example

@@ -0,0 +1,14 @@
+# API Configuration
+VITE_API_BASE_URL=http://localhost:8000
+VITE_API_TIMEOUT=10000
+
+# Application Configuration
+VITE_APP_TITLE=ROA Reports
+VITE_APP_VERSION=1.0.0
+
+# Telegram Bot Configuration
+VITE_TELEGRAM_BOT_USERNAME=roa2web_bot
+
+# Development Configuration
+VITE_DEBUG=true
+VITE_LOG_LEVEL=debug