Skip auto-memory hooks when project is not initialized

[severity1]

Summary

Auto-memory hooks should not trigger unless the project has been initialized via /auto-memory:init. Running on uninitialized projects wastes resources and may cause confusion.

Problem

Currently, load_config() in post-tool-use.py returns a default config when no config file exists:

def load_config(project_dir: str) -> dict:
    config_file = Path(project_dir) / ".claude" / "auto-memory" / "config.json"
    if config_file.exists():
        # ... load config
    return {"triggerMode": "default"}  # <-- defaults even when not initialized

This causes:

• Dirty files tracked on projects that have no auto-memory setup
• Stop hook may block and request memory-updater spawn on uninitialized projects
• Unnecessary file I/O and processing overhead
• Potential confusion when hooks fire unexpectedly

Proposed Solution

Treat missing config as "not enabled":

1. post-tool-use.py: Exit early if config file doesn't exist
2. stop.py: Exit early if config file doesn't exist

def load_config(project_dir: str) -> dict | None:
    """Load plugin configuration. Returns None if not initialized."""
    config_file = Path(project_dir) / ".claude" / "auto-memory" / "config.json"
    if not config_file.exists():
        return None  # Not initialized
    # ... load and return config

# In main():
config = load_config(project_dir)
if config is None:
    return  # Project not initialized, skip

Affected Files

• scripts/post-tool-use.py - add config existence check
• scripts/stop.py - add config existence check (for consistency)