v1.16.0

Two fixes for things that were quietly broken on a local ladder.

A local server that states its context window is believed

The chat-completions format has no field for a context window, so a target on
openaicompat had none: the context meter stayed blank and automatic
compaction, which is gated on the window, never fired. A session on a local
rung ran until the server refused a request.

The startup probe now reads the window where the server states one, under
max_context_length, loaded_context_length, context_length,
native_context_length, or vLLM's max_model_len. Those names do not mean the
same thing on every server, so the probe takes the smallest number stated:
guessing high sends requests the server rejects, while guessing low only
compacts earlier than it had to. A server whose list says nothing is asked once
for llama.cpp's /props, which reports the context actually allocated rather
than the length the model was trained at.

Where a server reports nothing at all, /context 32768 still sets it by hand.

The mouse belongs to the terminal until /mouse hands it over

Switchboard used to put the terminal into mouse-reporting mode at startup,
which is what stopped it selecting text. Dragging in the transcript or the
composer did nothing, and there was no way to copy anything out.

The mouse now stays with the terminal, so selection and copy work as they do
anywhere else. Nothing is lost: pgup and pgdn scroll a page, ctrl+u and
ctrl+d scroll half a page, home and end reach the ends of the transcript,
and ctrl+o expands the last route or tool entry, which is what a click on one
would have done.

If you want the wheel back, /mouse on returns it along with
click-to-expand, and takes selection away again. The setting persists as
[ui] mouse.

Full Changelog: v1.15.0...v1.16.0