Add comprehensive backend features and mobile UI improvements

Backend:
- Add 2FA authentication with TOTP support
- Add API keys management system
- Add audit logging for security events
- Add file upload/management system
- Add notifications system with preferences
- Add session management
- Add webhooks integration
- Add analytics endpoints
- Add export functionality
- Add password policy enforcement
- Add new database migrations for core tables

Frontend:
- Add module position system (top/bottom sidebar sections)
- Add search and notifications module configuration tabs
- Add mobile logo replacing hamburger menu
- Center page title absolutely when no tabs present
- Align sidebar footer toggles with navigation items
- Add lighter icon color in dark theme for mobile
- Add API keys management page
- Add notifications page with context
- Add admin analytics and audit logs pages

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/app/core/settings_registry.py

@@ -310,6 +310,57 @@ register_setting(SettingDefinition(
     category="auth"
 ))
 
+# Password policy settings
+register_setting(SettingDefinition(
+    key="password_min_length",
+    type=SettingType.INTEGER,
+    scope=SettingScope.GLOBAL,
+    storage=SettingStorage.DATABASE,
+    default=8,
+    description="Minimum password length",
+    category="security"
+))
+
+register_setting(SettingDefinition(
+    key="password_require_uppercase",
+    type=SettingType.BOOLEAN,
+    scope=SettingScope.GLOBAL,
+    storage=SettingStorage.DATABASE,
+    default=True,
+    description="Require uppercase letters in passwords",
+    category="security"
+))
+
+register_setting(SettingDefinition(
+    key="password_require_lowercase",
+    type=SettingType.BOOLEAN,
+    scope=SettingScope.GLOBAL,
+    storage=SettingStorage.DATABASE,
+    default=True,
+    description="Require lowercase letters in passwords",
+    category="security"
+))
+
+register_setting(SettingDefinition(
+    key="password_require_digit",
+    type=SettingType.BOOLEAN,
+    scope=SettingScope.GLOBAL,
+    storage=SettingStorage.DATABASE,
+    default=True,
+    description="Require digits in passwords",
+    category="security"
+))
+
+register_setting(SettingDefinition(
+    key="password_require_special",
+    type=SettingType.BOOLEAN,
+    scope=SettingScope.GLOBAL,
+    storage=SettingStorage.DATABASE,
+    default=False,
+    description="Require special characters in passwords",
+    category="security"
+))
+
 
 # =============================================================================
 # UI/LAYOUT SETTINGS (Global, Database)