Cleanup repo + harden offline install and watchdog

Repo hygiene:
- Remove dead scripts (.wait-for-display, .display-keepalive, .keep-screen-alive)
- Remove stale backup/scratch (install.sh.bak, New.txt, stale .pyc)
- Stop tracking machine-specific/generated state (config/app_config.json,
  playlists/server_playlist.json, src/player_auth.json, generated launchers)
- Prune duplicate wheel versions (one per package)
- Reorganize working_files -> dev/, dev/tests/, documentation/dev-notes/, scripts/
- Extend .gitignore; fix no-op rules in repo/.gitignore

Offline install (install.sh):
- Non-fatal system-dep step; per-package apt retry; .deb bundle install
- Skip pip self-upgrade offline; guard online fallbacks behind connectivity probe
- Dependency-free fetch_url (curl/wget/urllib); --no-reboot flag
- Fix corrupted literal backslash-bang escapes (shebangs, test -f, banner)
- Idempotent cron install (no more stacked @reboot lines)

Autostart / watchdog:
- start.sh: single-instance flock lock (.player_watchdog.lock) acquired only
  after a display is confirmed, preventing parallel watchdogs
- Set XDG_RUNTIME_DIR when missing; exit early if headless
- run_player.sh: activate .venv; stop_player.sh: clear lock file

dev/tests/test_server_playlist.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+"""Test script to check what playlist the server is actually returning."""
+
+import json
+import sys
+import os
+
+# Add src directory to path
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), 'src'))
+
+from get_playlists_v2 import fetch_server_playlist
+
+# Load config
+config_file = 'config/app_config.json'
+with open(config_file, 'r') as f:
+    config = json.load(f)
+
+print("=" * 80)
+print("TESTING SERVER PLAYLIST FETCH")
+print("=" * 80)
+
+# Fetch playlist from server
+print("\n1. Fetching playlist from server...")
+server_data = fetch_server_playlist(config)
+
+print(f"\n2. Server Response:")
+print(f"   Version: {server_data.get('version', 'N/A')}")
+print(f"   Playlist items: {len(server_data.get('playlist', []))}")
+
+print(f"\n3. Detailed Playlist Items:")
+for idx, item in enumerate(server_data.get('playlist', []), 1):
+    print(f"\n   Item {idx}:")
+    print(f"      file_name: {item.get('file_name', 'N/A')}")
+    print(f"      url: {item.get('url', 'N/A')}")
+    print(f"      duration: {item.get('duration', 'N/A')}")
+
+print("\n" + "=" * 80)
+print(f"TOTAL: Server has {len(server_data.get('playlist', []))} files")
+print("=" * 80)
+
+# Save to file for inspection
+output_file = 'server_response_debug.json'
+with open(output_file, 'w') as f:
+    json.dump(server_data, f, indent=2)
+print(f"\nFull server response saved to: {output_file}")