feat: multi Agent OS server support in AskUiControllerClient

[mlikasam-askui]

Summary

AskUiControllerClient can now manage multiple Agent OS servers (local
and/or remote) at once. One is active at a time and receives the agent's
actions; callers can switch at runtime or scope a switch to a with block.

New API:

• AgentOsServer (base), LocalAgentOsServer (replaces the old
  AskUiControllerServer — owns the local controller subprocess; auto-detects
  the Windows AskuiCoreService and switches to its port), RemoteAgentOsServer
  (already-running remote controller, no process management).
• AgentOsServerManager — enforces invariants: at most one local, unique
  session GUIDs / computer_ids / remote addresses.
• On AskUiControllerClient and exposed through AgentOs /
  ComputerAgentOsFacade: add_agent_os_server, add_remote_agent_os_server,
  list_agent_os_servers, get_active_agent_os_server,
  switch_agent_os_server, reset_agent_os_servers, temporary_select.
• AndroidAgentOs / PpadbAgentOs get a sibling temporary_select(device_sn).
• ComputerAgent auto-registers three new act() tools so the LLM can drive
  multi-target flows: ComputerListAgentOsServersTool,
  ComputerSwitchAgentOsServerTool, ComputerGetActiveAgentOsServerTool.
• LocalAgentOsServer and RemoteAgentOsServer are re-exported from the
  top-level askui package.
• Version bumped to 0.33.0.

New unit tests cover the server classes, the manager, the multi-target client,
and the new computer tools. The e2e test was updated to the new constructor.

Breaking changes

1. AskUiControllerServer removed. Use LocalAgentOsServer instead (same
   responsibility).

2. AskUiControllerClientSettings removed. The env vars
   ASKUI_CONTROLLER_CLIENT_SERVER_ADDRESS and
   ASKUI_CONTROLLER_CLIENT_SERVER_AUTOSTART no longer have any effect.
   Configure explicitly:

   AskUiControllerClient(
       agent_os_servers=[LocalAgentOsServer(address="127.0.0.1:24000")],
   )

   For the old "do not autostart" behavior, use RemoteAgentOsServer (never
   starts a process) or LocalAgentOsServer(is_service=True).

3. AskUiControllerClient.__init__ signature changed. Removed
   controller_server and settings; added
   agent_os_servers: list[AgentOsServer] | None. connect() now requires at
   least one registered server.

4. ComputerAgent.__init__ signature changed. Removed tools: AgentToolbox;
   added agent_os_servers: list[AgentOsServer] | None. Callers that injected
   a custom toolbox must subclass ComputerAgent or build the toolbox + agent
   themselves.

5. AgentOs gained 7 abstract-ish methods (default raises
   NotImplementedError). Non-AskUI backends (Playwright, custom) that don't
   override them will raise when the new computer tools call
   get_active_agent_os_server — which they do for screenshot,
   get_mouse_position, get_system_info, list_displays, and
   retrieve_active_display.

6. Computer tool output prefix changed. The five tools above now return
   "[Server with id '<computer_id>']: ...". Anything parsing the raw strings
   needs updating.

7. ToolCollection.get_agent_os_by_tags keyword renamed: tags →
   required_tags. Positional calls are unaffected.

8. Exception messages changed.

   • AskUiControllerOperationTimeoutError default message rewritten; when
     raised by _run_recorder_action it now includes the active server's
     description, session GUID, timeout window, retry count, and action class
     id.
   • AskUiControllerInvalidCommandError message reworded; details lines
     prefixed with Server details:.

   Tests asserting on exact message strings need updating.