fix: Per-agent terminal isolation, floating terminal z-index, and char-by-char input

- Add :key to PromptBar to force remount on agent switch, fixing shared terminal session bug
- Raise AgentTerminal z-index above PromptBar backdrop so floating terminal is visible/clickable
- Send prompt text char-by-char (15ms delay) matching FloatingVoice pattern for Claude Code compat
- Guard xterm dispose against unloaded addons to prevent errors on agent switch
- Widen PromptBar panel from 360px to 420px to fit all ChatInput buttons

.claude-ejecutor/plugins/known_marketplaces.json

@@ -5,6 +5,6 @@
       "repo": "anthropics/claude-plugins-official"
     },
     "installLocation": "C:\\Users\\jodar\\agent-ui\\.claude-ejecutor\\plugins\\marketplaces\\claude-plugins-official",
-    "lastUpdated": "2026-02-15T19:50:55.853Z"
+    "lastUpdated": "2026-02-16T06:32:07.237Z"
   }
 }