Add deploy command to upload and enable plugin bundles

- New deploy.go implements RunDeployCommand function
- Auto-discovers plugin bundle from ./dist/ folder based on manifest
- Supports --bundle-path flag for custom bundle location
- Reuses existing client connection logic for server authentication
- Updated main.go to register deploy command and add help documentation
- Follows existing patterns for error handling and structured logging

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

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

assets/build/deploy.mk

@@ -5,7 +5,7 @@
 ## Builds and installs the plugin to a server.
 .PHONY: deploy
 deploy: dist
-	./build/bin/pluginctl deploy  --bundle-path dist/$(BUNDLE_NAME)
+	pluginctl deploy --bundle-path dist/$(BUNDLE_NAME)
 
 ## Builds and installs the plugin to a server, updating the webapp automatically when changed.
 .PHONY: watch