Changes

This PR fixes issue #1282 where local .codegraphcontext/.env files incorrectly override global configuration in global/named context modes.

What Changed

• Modified load_config() in config_manager.py to respect context mode
• Added protection for DB_PATH_ENV_KEYS to prevent database path corruption
• Local .env files now only load in per-repo mode (or with CGC_LOAD_PROJECT_ENV=1)
• Added comprehensive unit tests in test_bug001_config_override.py
• Fixed VS Code extension warnings (removed deprecated activationEvents, added view icons)

Testing

• ✅ Global mode ignores local .env
• ✅ Per-repo mode uses local .env
• ✅ Environment variables override everything
• ✅ DB path keys are protected from override
• ✅ All existing tests pass

Impact

• Users in global/named mode are now protected from config hijacking
• Per-repo mode continues to work as intended
• Database integrity is protected
• E2E tests will now pass

Closes #1282