Fix critical bugs, security issues, and code quality across all modules

- Replace bare except clauses with specific exceptions (JSONDecodeError, IOError, ValueError, TypeError)
- Add path traversal protection restricting navigation to ALLOWED_BASE_DIR
- Sanitize iframe URLs with scheme validation and html.escape to prevent XSS
- Extract duplicate to_float/to_int to module-level helpers in json_loader.py
- Replace silent modulo wrapping with clamped bounds checking via get_batch_item()
- Remove hardcoded IP 192.168.1.51:5800, default to empty string
- Add try/except around fragile batch history string parsing
- Add JSON schema validation (dict type check) in read_json_data()
- Add Python logging framework, replace print() calls
- Consolidate session state initialization into loop with defaults dict
- Guard streamlit_agraph import with try/except ImportError
- Add backup snapshot before history node deletion
- Add cycle detection in HistoryTree.commit()

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

utils.py

@@ -1,8 +1,17 @@
 import json
+import logging
 import time
 from pathlib import Path
 import streamlit as st
 
+# Configure logging for the application
+logging.basicConfig(
+    level=logging.INFO,
+    format="%(asctime)s [%(name)s] %(levelname)s: %(message)s",
+    datefmt="%H:%M:%S",
+)
+logger = logging.getLogger(__name__)
+
 # Default structure for new files
 DEFAULTS = {
     # --- Standard Keys for your Restored Single Tab ---
@@ -43,14 +52,17 @@ DEFAULTS = {
 CONFIG_FILE = Path(".editor_config.json")
 SNIPPETS_FILE = Path(".editor_snippets.json")
 
+# Restrict directory navigation to this base path (resolve symlinks)
+ALLOWED_BASE_DIR = Path.cwd().resolve()
+
 def load_config():
     """Loads the main editor configuration (Favorites, Last Dir, Servers)."""
     if CONFIG_FILE.exists():
         try:
             with open(CONFIG_FILE, 'r') as f:
                 return json.load(f)
-        except:
-            pass
+        except (json.JSONDecodeError, IOError) as e:
+            logger.warning(f"Failed to load config: {e}")
     return {"favorites": [], "last_dir": str(Path.cwd()), "comfy_instances": []}
 
 def save_config(current_dir, favorites, extra_data=None):
@@ -76,8 +88,8 @@ def load_snippets():
         try:
             with open(SNIPPETS_FILE, 'r') as f:
                 return json.load(f)
-        except:
-            pass
+        except (json.JSONDecodeError, IOError) as e:
+            logger.warning(f"Failed to load snippets: {e}")
     return {}
 
 def save_snippets(snippets):