Add USB, Notifications, Network plugins and reusable EmployeeSearch component

New Plugins:
- USB plugin: Device checkout/checkin with employee lookup, checkout history
- Notifications plugin: Announcements with types, scheduling, shopfloor display
- Network plugin: Network device management with subnets and VLANs
- Equipment and Computers plugins: Asset type separation

Frontend:
- EmployeeSearch component: Reusable employee lookup with autocomplete
- USB views: List, detail, checkout/checkin modals
- Notifications views: List, form with recognition mode
- Network views: Device list, detail, form
- Calendar view with FullCalendar integration
- Shopfloor and TV dashboard views
- Reports index page
- Map editor for asset positioning
- Light/dark mode fixes for map tooltips

Backend:
- Employee search API with external lookup service
- Collector API for PowerShell data collection
- Reports API endpoints
- Slides API for TV dashboard
- Fixed AppVersion model (removed BaseModel inheritance)
- Added checkout_name column to usbcheckouts table

Styling:
- Unified detail page styles
- Improved pagination (page numbers instead of prev/next)
- Dark/light mode theme improvements

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

plugins/usb/plugin.py

@@ -0,0 +1,80 @@
+"""USB plugin main class."""
+
+import json
+import logging
+from pathlib import Path
+from typing import List, Dict, Optional, Type
+
+from flask import Flask, Blueprint
+
+from shopdb.plugins.base import BasePlugin, PluginMeta
+from shopdb.extensions import db
+
+from .models import USBCheckout
+from .api import usb_bp
+
+logger = logging.getLogger(__name__)
+
+
+class USBPlugin(BasePlugin):
+    """
+    USB plugin - manages USB device checkouts.
+    
+    USB devices are stored in the machines table (machinetypeid=44).
+    This plugin provides checkout/checkin tracking.
+    """
+    
+    def __init__(self):
+        self._manifest = self._load_manifest()
+    
+    def _load_manifest(self) -> Dict:
+        """Load plugin manifest from JSON file."""
+        manifest_path = Path(__file__).parent / 'manifest.json'
+        if manifest_path.exists():
+            with open(manifest_path, 'r') as f:
+                return json.load(f)
+        return {}
+    
+    @property
+    def meta(self) -> PluginMeta:
+        """Return plugin metadata."""
+        return PluginMeta(
+            name=self._manifest.get('name', 'usb'),
+            version=self._manifest.get('version', '1.0.0'),
+            description=self._manifest.get('description', 'USB device checkout management'),
+            author=self._manifest.get('author', 'ShopDB Team'),
+            dependencies=self._manifest.get('dependencies', []),
+            core_version=self._manifest.get('core_version', '>=1.0.0'),
+            api_prefix=self._manifest.get('api_prefix', '/api/usb'),
+        )
+    
+    def get_blueprint(self) -> Optional[Blueprint]:
+        """Return Flask Blueprint with API routes."""
+        return usb_bp
+    
+    def get_models(self) -> List[Type]:
+        """Return list of SQLAlchemy model classes."""
+        return [USBCheckout]
+    
+    def init_app(self, app: Flask, db_instance) -> None:
+        """Initialize plugin with Flask app."""
+        logger.info(f"USB plugin initialized (v{self.meta.version})")
+    
+    def on_install(self, app: Flask) -> None:
+        """Called when plugin is installed."""
+        logger.info("USB plugin installed")
+    
+    def on_uninstall(self, app: Flask) -> None:
+        """Called when plugin is uninstalled."""
+        logger.info("USB plugin uninstalled")
+    
+    def get_navigation_items(self) -> List[Dict]:
+        """Return navigation menu items."""
+        return [
+            {
+                'name': 'USB Devices',
+                'icon': 'usb',
+                'route': '/usb',
+                'position': 45,
+            },
+        ]