feat: implement production-ready MUC operations and comprehensive testing

- Implement proper XMPP MUC operations using mellium.im/xmpp/muc package
- Add session readiness checking to prevent blocking on room joins
- Create comprehensive bridge manager architecture with lifecycle management
- Add complete channel mapping functionality with KV store persistence
- Remove defensive logger nil checks as requested by user
- Enhance XMPP client doctor with MUC testing (join/wait/leave workflow)
- Add detailed dev server documentation for test room creation
- Implement timeout protection for all MUC operations
- Add proper error handling with fmt.Errorf instead of pkg/errors
- Successfully tested: MUC join in ~21ms, 5s wait, clean leave operation

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

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

server/model/bridge.go

@@ -1,16 +1,62 @@
 package model
 
+type BridgeManager interface {
+	// RegisterBridge registers a bridge with the given name. Returns an error if the name is empty,
+	// the bridge is nil, or a bridge with the same name is already registered.
+	RegisterBridge(name string, bridge Bridge) error
+
+	// StartBridge starts the bridge with the given name. Returns an error if the bridge
+	// is not registered or fails to start.
+	StartBridge(name string) error
+
+	// StopBridge stops the bridge with the given name. Returns an error if the bridge
+	// is not registered or fails to stop.
+	StopBridge(name string) error
+
+	// UnregisterBridge removes the bridge with the given name from the manager.
+	// The bridge is stopped before removal if it's currently connected.
+	// Returns an error if the bridge is not registered.
+	UnregisterBridge(name string) error
+
+	// GetBridge retrieves the bridge instance with the given name.
+	// Returns an error if the bridge is not registered.
+	GetBridge(name string) (Bridge, error)
+
+	// ListBridges returns a list of all registered bridge names.
+	ListBridges() []string
+
+	// HasBridge checks if a bridge with the given name is registered.
+	HasBridge(name string) bool
+
+	// HasBridges checks if any bridges are currently registered.
+	HasBridges() bool
+
+	// Shutdown stops and unregisters all bridges. Returns an error if any bridge
+	// fails to stop, but continues to attempt stopping all bridges.
+	Shutdown() error
+
+	// OnPluginConfigurationChange propagates configuration changes to all registered bridges.
+	// Returns an error if any bridge fails to update its configuration, but continues to
+	// attempt updating all bridges.
+	OnPluginConfigurationChange(config any) error
+}
+
 type Bridge interface {
 	// UpdateConfiguration updates the bridge configuration
 	UpdateConfiguration(config any) error
+
 	// Start starts the bridge
 	Start() error
+
 	// Stop stops the bridge
 	Stop() error
+
 	// CreateChannelRoomMapping creates a mapping between a Mattermost channel ID and an bridge room ID.
 	CreateChannelRoomMapping(channelID, roomJID string) error
+
 	// GetChannelRoomMapping retrieves the bridge room ID for a given Mattermost channel ID.
 	GetChannelRoomMapping(channelID string) (string, error)
+
 	// IsConnected checks if the bridge is connected to the remote service.
 	IsConnected() bool
 }