Rename Kill to Close, add New Terminal palette entry, clean up exited terminals

- Palette's per-child "Kill <name>" action is now labelled "Close <name>"
  (action kind unchanged; still SIGTERM). Matches the existing "Close
  agent: …" context entry and reads less violent for a graceful term.
- New "New Terminal" palette entry spawns a bare interactive $SHELL pane
  via LaunchTerminal (kind=terminal). Replaces the default "shell"
  process preset that was seeded on first run.
- Exited KindTerminal entries are now dropped from the session in
  reapChild — terminals have no restart path, so leaving them behind as
  greyed rows in the Processes sidebar was just clutter. processList
  also filters defensively.

TODO.md

@@ -1,6 +1,3 @@
-- [ ] We should probably rename the Kill <Process> terminology to Close <Process> instead, across processes and agents.
-- [ ] Exited shells are still being treated as active processes. They should be removed from the process list when they exit.
-- [ ] Shells should be renamed to terminals. "New Terminal" etc.
 - [ ] Codex seemed to think that it needed to launch patterm itself to get the mcp working
 - [ ] I cant click and drag to select text from codex
 - [ ] codex uses perl to interact with the socket rather than calling mcp tools
@@ -12,6 +9,7 @@
 - [ ] Resuming a long claude session takes a couple of seconds for the entire buffer to load in, it looks like it's scrolling down for a couple seconds.
   - In raw alacritty this is instant, so there's some sort of performance issue with patterm's terminal emulation.
 
+
 # On Hold
 - [ ] There's a unicode <?> being displayed in opencode [ON HOLD]
   - Investigated 2026-05-14: patterm passes ghostty grapheme codepoints