feat: add status line with agent display + fix pa-mode keybind

Status line shows: [agent-name] Model | X% context
- Added statusline.sh script that reads CLAUDE_AGENT env var
- Configured settings.json to use the status line script

Fixed pa-mode keybind issue (terminal closing immediately):
- Changed from detached session + attach to exec tmux -A
- Using exec replaces shell process, keeping terminal open
- Added CLAUDE_AGENT env var export for status line

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

automation/statusline.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# Claude Code Status Line - displays agent, model, and context usage
+input=$(cat)
+
+AGENT="${CLAUDE_AGENT:-}"
+MODEL=$(echo "$input" | jq -r '.model.display_name // "?"')
+
+# Calculate context percentage
+CONTEXT_PCT="?"
+usage=$(echo "$input" | jq '.context_window.current_usage // empty')
+if [ -n "$usage" ]; then
+  current=$(echo "$usage" | jq '.input_tokens + .cache_creation_input_tokens + .cache_read_input_tokens')
+  size=$(echo "$input" | jq '.context_window.context_window_size')
+  if [ "$size" -gt 0 ] 2>/dev/null; then
+    CONTEXT_PCT=$((current * 100 / size))
+  fi
+fi
+
+if [ -n "$AGENT" ]; then
+  echo "[$AGENT] $MODEL | ${CONTEXT_PCT}% context"
+else
+  echo "$MODEL | ${CONTEXT_PCT}% context"
+fi