Do not allow agent to ask custom-less questions

Improvements

• CoreImprove prompt for explore agent
• CoreAdd plugin mocks to provider tests@vglafirov
• CoreUpdate User-Agent string to latest Chrome version in webfetch@AlanThiec
• CoreAdd plan mode with enter and exit tools
• CoreAdd family to GPT 5.2 Codex in Codex plugin
• CoreAdd GitLab Duo Agentic Chat provider support@vglafirov
• CoreDelete key from recordsByKey on instance disposal@sauerdaniel
• CoreClose existing MCP client before reassignment to prevent resource leaks@sauerdaniel
• CoreAdded Ask Question tool support for desktop application@dbpolito
• TerminalTweak external directory permission rendering in TUI
• TerminalEnsure external directory and Bash tool invocations render working directory details
• TerminalFix duplicate radio button icon in MCP auth CLI interface@dmmulroy
• DesktopHandle Shift+Enter before IME check to prevent stuck state in prompt input@josephbharrison
• DesktopRevert provider icon on select model dialog in desktop app@dbpolito