Update version number to 2.0.6 across codebase

- Fix version inconsistencies in server.js API status endpoint
- Update User-Agent string in RSS feed manager
- Update version in config file templates
- Update dashboard display with version 2.0.6
- Add version 2.0.6 to version history with changelog

🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>

.env.install

@@ -0,0 +1,8 @@
+export TRANSMISSION_REMOTE=true
+export TRANSMISSION_HOST="myserver.example.com"
+export TRANSMISSION_PORT="9091"
+export TRANSMISSION_USER="username"
+export TRANSMISSION_PASS="password"
+export TRANSMISSION_RPC_PATH="/transmission/rpc"
+export REMOTE_DOWNLOAD_DIR="/var/lib/transmission-daemon/downloads"
+export LOCAL_DOWNLOAD_DIR="/mnt/downloads"