refactor: extract remote-daemon stack out of Workspace.swift

Workspace.swift carried ~4,900 lines of self-contained remote-session
infrastructure declared before the Workspace class even began — pending
call registry, RPC client, loopback HTTP rewriters, proxy tunnel, SOCKS
broker, CLI relay server, and the session controller. Its only edge
back to Workspace is the weak reference held by
WorkspaceRemoteSessionController.

Pure move, no logic changes:
- Sources/WorkspaceRemoteDaemon.swift — transport/infra types
- Sources/WorkspaceRemoteSession.swift — WorkspaceRemoteSessionController
- Workspace.swift shrinks 12,352 -> 7,438 lines

Visibility widened from file-scope to internal only where the move
splits an existing same-file reference: three transport classes used by
the session controller, RemoteDropUploadError, and five Workspace
apply* callbacks plus activeRemoteSessionControllerID used by the moved
controller.

Author: arzafran

GhosttyTabs.xcodeproj/project.pbxproj

@@ -39,6 +39,8 @@
 		A5001290 /* MarkdownUI in Frameworks */ = {isa = PBXBuildFile; productRef = A5001291 /* MarkdownUI */; };
 		A5001405 /* PanelContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001415 /* PanelContentView.swift */; };
 		A5001406 /* Workspace.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001416 /* Workspace.swift */; };
+		A5FF0012 /* WorkspaceRemoteSession.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5FF0002 /* WorkspaceRemoteSession.swift */; };
+		A5FF0011 /* WorkspaceRemoteDaemon.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5FF0001 /* WorkspaceRemoteDaemon.swift */; };
 		A5001407 /* WorkspaceContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001417 /* WorkspaceContentView.swift */; };
 			A5001093 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001090 /* AppDelegate.swift */; };
 			A5001094 /* NotificationsPage.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001091 /* NotificationsPage.swift */; };
@@ -238,6 +240,8 @@
 		A5001418 /* MarkdownPanel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Panels/MarkdownPanel.swift; sourceTree = "<group>"; };
 		A5001419 /* MarkdownPanelView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Panels/MarkdownPanelView.swift; sourceTree = "<group>"; };
 		A5001416 /* Workspace.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Workspace.swift; sourceTree = "<group>"; };
+		A5FF0002 /* WorkspaceRemoteSession.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WorkspaceRemoteSession.swift; sourceTree = "<group>"; };
+		A5FF0001 /* WorkspaceRemoteDaemon.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WorkspaceRemoteDaemon.swift; sourceTree = "<group>"; };
 		A5001417 /* WorkspaceContentView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WorkspaceContentView.swift; sourceTree = "<group>"; };
 		A5001090 /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
 		A5001091 /* NotificationsPage.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NotificationsPage.swift; sourceTree = "<group>"; };
@@ -463,6 +467,8 @@
 					A5001013 /* TabManager.swift */,
 					A5001511 /* UITestRecorder.swift */,
 					A5001416 /* Workspace.swift */,
+					A5FF0002 /* WorkspaceRemoteSession.swift */,
+					A5FF0001 /* WorkspaceRemoteDaemon.swift */,
 				A5001417 /* WorkspaceContentView.swift */,
 				A5001014 /* GhosttyConfig.swift */,
 				A5001015 /* GhosttyTerminalView.swift */,
@@ -768,6 +774,8 @@
 						A5001003 /* TabManager.swift in Sources */,
 						A5001501 /* UITestRecorder.swift in Sources */,
 						A5001406 /* Workspace.swift in Sources */,
+						A5FF0012 /* WorkspaceRemoteSession.swift in Sources */,
+						A5FF0011 /* WorkspaceRemoteDaemon.swift in Sources */,
 				A5001407 /* WorkspaceContentView.swift in Sources */,
 				A5001004 /* GhosttyConfig.swift in Sources */,
 				A5001005 /* GhosttyTerminalView.swift in Sources */,