fix: v0.10.3 no tmux right-click menus; close split panes

Right-clicking a pane opened tmux's menu, whose Split entries left a stray
pane next to Claude (and whose Kill entries could end it). Unbind the
right-click menus; add --unsplit and a palette entry that closes extra
panes and keeps Claude's. Closes #52

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WHRLCCdXYm41Qx5kNhehaP

debian/changelog

@@ -1,3 +1,12 @@
+devdesk (0.10.3) bookworm; urgency=medium
+
+  * No tmux right-click menus (#52). A stray click on one split a pane, or
+    could kill Claude's window. "Close split panes (keeps Claude)" in the
+    command palette, backed by `--unsplit`, removes a split that happened
+    anyway.
+
+ -- Jared Vititoe <jjvititoe1@gmail.com>  Tue, 13 Oct 2026 09:00:00 -0400
+
 devdesk (0.10.2) bookworm; urgency=medium
 
   * Selecting text in the terminal works like a normal terminal (#51). A