Add eagle-logs helper for tailing active instance logs (#5571)

Usage:
  eagle-logs           # Tail logs (follow mode)
  eagle-logs -n 100    # Show last 100 lines and follow
  eagle-logs --no-follow -n 50   # Last 50 lines without following

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

scripts/eagle-logs.sh

@@ -0,0 +1,44 @@
+#!/bin/bash
+#
+# Helper to tail logs from the active Eagle instance.
+# Reads the active instance from /opt/eagle0/.active-instance (set by deploy-blue-green.sh).
+#
+# Usage:
+#   eagle-logs           # Tail logs (follow mode)
+#   eagle-logs -n 100    # Show last 100 lines and follow
+#   eagle-logs --no-follow -n 50   # Show last 50 lines without following
+#
+# To create an alias, add to ~/.bashrc:
+#   alias eagle-logs='/opt/eagle0/scripts/eagle-logs.sh'
+#
+
+set -euo pipefail
+
+APP_DIR="${APP_DIR:-/opt/eagle0}"
+ACTIVE_FILE="${APP_DIR}/.active-instance"
+
+# Read active instance from file, with fallback
+if [ -f "$ACTIVE_FILE" ]; then
+    ACTIVE=$(cat "$ACTIVE_FILE")
+else
+    # Fallback: check which container is actually running
+    if docker inspect --format='{{.State.Running}}' eagle-blue 2>/dev/null | grep -q true; then
+        ACTIVE="eagle-blue"
+    elif docker inspect --format='{{.State.Running}}' eagle-green 2>/dev/null | grep -q true; then
+        ACTIVE="eagle-green"
+    else
+        ACTIVE=""
+    fi
+fi
+
+if [ -z "$ACTIVE" ]; then
+    echo "Error: No active Eagle instance found" >&2
+    exit 1
+fi
+
+# Default to follow mode if no args provided
+if [ $# -eq 0 ]; then
+    exec docker logs -f "$ACTIVE"
+else
+    exec docker logs "$@" "$ACTIVE"
+fi