Initial import: shopdb-flask multi-site asset platform

Flask + Vue rewrite of the classic-ASP shopdb, built as a plugin
framework so sister GE Aerospace sites can adopt it. Product version
0.7.0-pre-0.8.0, plugin contract 0.11.0, 966 backend tests.

Key entry points:
- docs/INSTALL-WINDOWS-IIS.md - tested Windows + IIS install runbook
  (own-site and subpath deployment methods)
- docs/PILOT-DEPLOY.md - production pilot: stand up + import + verify
- docs/IMPORT-API.md - schema-agnostic legacy data import contract
- scripts/site_imports/wjf/ - West Jefferson reference import loader
- docs/adr/ - twelve accepted architecture decision records

shopdb/plugins/registry.py

@@ -0,0 +1,140 @@
+"""Plugin registry for tracking installed and enabled plugins."""
+
+import json
+from pathlib import Path
+from typing import Dict, List, Optional
+from dataclasses import dataclass, field, asdict
+from datetime import datetime, timezone
+
+
+@dataclass
+class PluginState:
+    """Persistent state for a plugin."""
+
+    name: str
+    version: str
+    installed_at: str
+    enabled: bool = True
+    migrations_applied: List[str] = field(default_factory=list)
+    config: Dict = field(default_factory=dict)
+
+
+class PluginRegistry:
+    """
+    Manages plugin state persistence.
+    Stores state in JSON file in instance folder.
+    """
+
+    def __init__(self, state_file: Path):
+        self.state_file = state_file
+        self._plugins: Dict[str, PluginState] = {}
+        self._load()
+
+    def _load(self) -> None:
+        """Load registry from file."""
+        if self.state_file.exists():
+            try:
+                with open(self.state_file, 'r') as f:
+                    data = json.load(f)
+                    for name, state_data in data.get('plugins', {}).items():
+                        self._plugins[name] = PluginState(**state_data)
+            except (json.JSONDecodeError, TypeError):
+                # Corrupted file, start fresh
+                self._plugins = {}
+        self._migrate_renamed_plugins()
+
+    def _migrate_renamed_plugins(self) -> None:
+        """Upgrade path for the equipment -> machines plugin rename.
+
+        Existing installs carry an 'equipment' entry in plugins.json. When the
+        renamed plugins/machines directory exists and no 'machines' entry does,
+        carry the state over under the new name and persist.
+        """
+        if 'equipment' not in self._plugins or 'machines' in self._plugins:
+            return
+        machines_dir = Path(__file__).resolve().parents[2] / 'plugins' / 'machines'
+        if not machines_dir.exists():
+            return
+        state = self._plugins.pop('equipment')
+        state.name = 'machines'
+        self._plugins['machines'] = state
+        self._save()
+
+    def _save(self) -> None:
+        """Save registry to file."""
+        self.state_file.parent.mkdir(parents=True, exist_ok=True)
+        with open(self.state_file, 'w') as f:
+            json.dump({
+                'plugins': {
+                    name: asdict(state)
+                    for name, state in self._plugins.items()
+                }
+            }, f, indent=2)
+
+    def register(self, name: str, version: str, enabled: bool = True) -> PluginState:
+        """Register a newly installed plugin. enabled=False leaves it off until a
+        site opts in (used for plugins that provision extra tables)."""
+        state = PluginState(
+            name=name,
+            version=version,
+            installed_at=datetime.now(timezone.utc).replace(tzinfo=None).isoformat(),
+            enabled=enabled
+        )
+        self._plugins[name] = state
+        self._save()
+        return state
+
+    def unregister(self, name: str) -> None:
+        """Remove plugin from registry."""
+        if name in self._plugins:
+            del self._plugins[name]
+            self._save()
+
+    def get(self, name: str) -> Optional[PluginState]:
+        """Get plugin state."""
+        return self._plugins.get(name)
+
+    def is_installed(self, name: str) -> bool:
+        """Check if plugin is installed."""
+        return name in self._plugins
+
+    def is_enabled(self, name: str) -> bool:
+        """Check if plugin is enabled."""
+        state = self._plugins.get(name)
+        return state.enabled if state else False
+
+    def enable(self, name: str) -> None:
+        """Enable a plugin."""
+        if name in self._plugins:
+            self._plugins[name].enabled = True
+            self._save()
+
+    def disable(self, name: str) -> None:
+        """Disable a plugin."""
+        if name in self._plugins:
+            self._plugins[name].enabled = False
+            self._save()
+
+    def get_enabled_plugins(self) -> List[str]:
+        """Get list of enabled plugin names."""
+        return [
+            name for name, state in self._plugins.items()
+            if state.enabled
+        ]
+
+    def add_migration(self, name: str, revision: str) -> None:
+        """Record that a migration was applied."""
+        if name in self._plugins:
+            if revision not in self._plugins[name].migrations_applied:
+                self._plugins[name].migrations_applied.append(revision)
+                self._save()
+
+    def get_all(self) -> Dict[str, PluginState]:
+        """Get all registered plugins."""
+        return self._plugins.copy()
+
+    def update_config(self, name: str, config: Dict) -> None:
+        """Update plugin configuration."""
+        if name in self._plugins:
+            self._plugins[name].config.update(config)
+            self._save()