feat: v2.0 — card UI, AI agents (Claude/DeepSeek), collapsible commands

Major update:
- Card-based session layout with colored group indicators
- AI agent: Claude API, DeepSeek API, local keyword search
- Collapsible command panel — more space for agent
- macOS build script (build_mac.sh)
- Updated README with Windows/macOS install instructions
- Config persistence in pca_config.json

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

install.bat

@@ -1,5 +1,5 @@
 @echo off
-echo === KU SSH Manager — Install and Run ===
+echo === PCA SSH v2.0 — Install and Run ===
 
 where python >nul 2>&1
 if errorlevel 1 (
@@ -13,5 +13,5 @@ if errorlevel 1 (
 echo Installing dependencies...
 pip install paramiko
 
-echo Starting SSH Manager...
+echo Starting PCA SSH...
 python ssh_manager.py