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.

internal/app/palette.go

@@ -11,12 +11,13 @@ import (
 // paletteAction is what the palette returns when the user picks an item.
 type paletteAction struct {
 	// kind: "spawn-agent" | "spawn-process" | "spawn-process-form" |
-	//       "spawn-process-submit" | "switch" | "kill" | "quit" |
-	//       "cancel" | "pad-delete" | "pad-rename" | "pad-rename-form" |
-	//       "pad-rename-submit" | "pad-edit" | "agent-rename" |
-	//       "agent-rename-form" | "agent-rename-submit" | "agent-close" |
-	//       "proc-rename" | "proc-rename-form" | "proc-rename-submit" |
-	//       "proc-delete" | "proc-stop" | "proc-restart"
+	//       "spawn-process-submit" | "spawn-terminal" | "switch" |
+	//       "kill" | "quit" | "cancel" | "pad-delete" | "pad-rename" |
+	//       "pad-rename-form" | "pad-rename-submit" | "pad-edit" |
+	//       "agent-rename" | "agent-rename-form" | "agent-rename-submit" |
+	//       "agent-close" | "proc-rename" | "proc-rename-form" |
+	//       "proc-rename-submit" | "proc-delete" | "proc-stop" |
+	//       "proc-restart"
 	kind string
 
 	// For spawn-agent / spawn-process, the preset to launch.
@@ -276,6 +277,16 @@ func (p *paletteState) allItems() []paletteItem {
 		})
 	}
 
+	// "New Terminal" — bare interactive $SHELL pane. Distinct from
+	// "Run process: …" presets in that it spawns a KindTerminal (which
+	// disappears from the sidebar on exit rather than sticking around
+	// for restart). One quick keystroke; no form.
+	out = append(out, paletteItem{
+		label:  "New Terminal",
+		hint:   "bare interactive $SHELL · removed on exit",
+		action: paletteAction{kind: "spawn-terminal"},
+	})
+
 	// Freeform "Spawn process…" entry. Opens a sub-form for typing an
 	// arbitrary command line and ticking "relaunch on exit". The action
 	// kind is intercepted by acceptOrEnterForm so accept switches the
@@ -288,14 +299,14 @@ func (p *paletteState) allItems() []paletteItem {
 		action: paletteAction{kind: "spawn-process-form"},
 	})
 
-	// Kill entries last among the action rows, before Quit. Mirror the
+	// Close entries last among the action rows, before Quit. Mirror the
 	// "(current)" marker from switch entries so the focused tab is
-	// obvious when scanning the kill list.
+	// obvious when scanning the close list.
 	for _, c := range p.children {
 		if c.Status() != StatusRunning {
 			continue
 		}
-		label := "Kill " + c.DisplayName()
+		label := "Close " + c.DisplayName()
 		if c.ID == p.focused {
 			label = "• " + label + " (current)"
 		}