v2.1.2

release: v2.1.2 (#536)

Release **v2.1.2**.

Merging creates the `v2.1.2` tag and triggers the release build.

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- **Scrolling works in fullscreen pi.** pi 1.0 runs fullscreen and
handles the mouse wheel itself; gmux now restores its mouse modes when
you open, switch to, or reload a session, so the wheel scrolls the
transcript instead of cycling prompt history
([#538](https://github.com/gmuxapp/gmux/pull/538)).
- **Less data on mobile.** The session stream, scrollback replay, JSON
responses and the web bundle are gzip-compressed over the network
(session list ~6.5× smaller, scrollback ~20×). Disable with `[http]
compression = false` or `GMUXD_HTTP_COMPRESS=0`
([#533](https://github.com/gmuxapp/gmux/pull/533)).
- **pi 1.0 compatibility.** `pi mcp …` and `pi -v` run as plain commands
instead of starting an agent session
([#539](https://github.com/gmuxapp/gmux/pull/539)).

### Upgrade notes

- Sessions that were already running keep their old runner until
restarted. To get the scrolling fix in an existing fullscreen pi
session, kill and resume it (or start a new one).
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### Features
- gzip on the phone path — SSE stream, scrollback replay, JSON and the
web bundle ([#533](https://github.com/gmuxapp/gmux/pull/533))

### Fixes
- **(terminal)** restore mouse/input modes on checkpoint so wheel in
fullscreen pi scrolls ([#538](https://github.com/gmuxapp/gmux/pull/538))
- **(adapter)** handle pi 1.0 `mcp` subcommand and `-v` info flag
([#539](https://github.com/gmuxapp/gmux/pull/539))
- **(web)** first scroll after a reflow no longer jumps back to the last
hand-scrolled row ([#541](https://github.com/gmuxapp/gmux/pull/541))
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Co-authored-by: mgabor3141 <9047995+mgabor3141@users.noreply.github.com>