docs(fix[control-mode]): Clarify internal session naming

why: Align control-mode docs with the UUID-based internal session name and runnable examples.
what:
- Update CHANGES and control-mode docs to use libtmux_ctrl_XXXXXXXX naming
- Fix the attach-session example to define a bootstrap Server

Author: tony

CHANGES

@@ -148,7 +148,7 @@ The following deprecations from 0.50.0 continue to emit {class}`DeprecationWarni
 - Internal control session is automatically filtered from `Server.sessions` /
   `Server.has_session()`; advanced users can inspect all sessions via
   `Server._sessions_all()`.
-- `ControlModeEngine` accepts `internal_session_name` (default `libtmux_control_mode`)
+- `ControlModeEngine` accepts `internal_session_name` (default `libtmux_ctrl_XXXXXXXX`)
   and `control_session` for advanced connection strategies.
 
 Example:
@@ -191,7 +191,7 @@ for notif in engine.iter_notifications(timeout=0.1):
 ### Compatibility
 
 - Control mode internal session filtering is engine-driven; callers no longer need
-  to manually exclude `libtmux_control_mode`. APIs stay unchanged; additional metadata
+  to manually exclude `libtmux_ctrl_*`. APIs stay unchanged; additional metadata
   is attached for advanced users. (#605)
 
 ## libtmux 0.50.1 (2025-12-06)

docs/topics/control_mode.md

@@ -43,7 +43,7 @@ for notif in engine.iter_notifications(timeout=0.1):
 
 :::{note}
 Control mode creates an internal session for connection management (default name:
-`libtmux_control_mode`). This session is automatically filtered from
+`libtmux_ctrl_XXXXXXXX`). This session is automatically filtered from
 `Server.sessions` and `Server.has_session()` to maintain engine transparency.
 :::
 
@@ -97,8 +97,9 @@ For expert use cases, control mode can attach to an existing session instead of
 creating an internal one:
 
 ```python
-# Create a session first
-server.new_session("shared")
+# Create a session first (subprocess engine by default)
+bootstrap = Server()
+bootstrap.new_session("shared", attach=False)
 
 # Control mode attaches to it for its connection
 engine = ControlModeEngine(control_session="shared")