remove AbstractCliManager dead code

[parsakhaz]

the abstract cli manager and its subclasses (claudeCodeManager, codexManager, claudePanelManager, codexPanelManager, AbstractAIPanelManager) are old code from before claude/codex panels were migrated to xterm.js terminal panels. they have their own pty spawn and resize paths that are no longer used at runtime. should be removed to avoid confusion (i just spent time tracing a resize bug through them before realizing they're dead).

files to audit and likely remove:

• main/src/services/panels/cli/AbstractCliManager.ts
• main/src/services/panels/claude/claudeCodeManager.ts
• main/src/services/panels/claude/claudePanelManager.ts
• main/src/services/panels/codex/codexManager.ts
• main/src/services/panels/codex/codexPanelManager.ts
• main/src/services/panels/ai/AbstractAIPanelManager.ts
• main/src/ipc/claudePanel.ts
• main/src/ipc/codexPanel.ts
• main/src/ipc/baseAIPanelHandler.ts