Add plugin auto-build and hot reload for dev

[Diddyy]

Adds DevPluginPaths config so the emulator loads plugins directly from their build output directory — no more copying DLLs into plugins/ during development.

Dev workflow:

1. Point DevPluginPaths at your plugin's bin/Debug/net9.0
2. Run dotnet watch build in your plugin project
3. Edit, save, auto-rebuild, auto-reload — clients stay connected

Changes:

• DevPluginPaths in PluginConfig — emulator discovers plugins from build output
• Hot-reload watcher monitors both plugins/ and dev paths
• ALC unload failures now log warnings instead of failing silently
• Added README documenting the full plugin dev setup

[Copilot]

Pull request overview

This PR adds development-only plugin hot reload and auto-build capabilities to improve the plugin development workflow when debugging Turbo.Main. The changes introduce file system watchers that monitor plugin artifacts and source code, automatically rebuilding and reloading plugins when changes are detected. These features are only enabled in the Development environment via configuration.

Changes:

• Added ReloadAsync(string key) method to PluginManager for targeted single-plugin reloads
• Implemented PluginHotReloadService to watch plugin artifact folders and trigger reloads on file changes
• Implemented PluginAutoBuildService to watch plugin source folders and trigger dotnet builds on code changes
• Wired up console commands reload-plugins and reload-plugin <key> for manual plugin management

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
Turbo.Plugins/PluginManager.cs	Added ReloadAsync method for single-plugin reloads and extracted RebuildDependents helper
Turbo.Plugins/PluginHotReloadService.cs	New hosted service that watches plugin artifacts and debounces reload requests
Turbo.Plugins/PluginAutoBuildService.cs	New hosted service that watches plugin source files and triggers auto-builds
Turbo.Plugins/Extensions/ServiceCollectionExtensions.cs	Conditionally registers hot reload and auto-build services in Development environment
Turbo.Plugins/Configuration/PluginConfig.cs	Added configuration properties for hot reload and auto-build features
Turbo.Main/Console/ConsoleCommandService.cs	Implemented reload-plugins and reload-plugin commands with proper usage messages

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