Ship the Tech Tools plugin that the previous export silently dropped

plugins/tools/plugin.py

@@ -0,0 +1,56 @@
+"""Tech Tools plugin.
+
+A section for small technician utilities. Every tool here runs entirely in the
+browser: no API, no tables, no state. That is deliberate - these are the things
+someone reaches for at a bench with no network guarantee, and an air-gapped
+site gets them for free.
+
+The plugin exists so the section can carry a nav entry and be included in or
+left out of a per-site build (ADR-013). The tools themselves are frontend-only,
+which is why get_blueprint and get_models are both empty.
+"""
+
+import logging
+from typing import List, Optional, Type
+
+from flask import Blueprint, Flask
+
+from shopdb.plugins.base import BasePlugin, PluginMeta
+
+logger = logging.getLogger(__name__)
+
+
+class ToolsPlugin(BasePlugin):
+    """Registers the Tech Tools section. All tools are client-side."""
+
+    @property
+    def meta(self) -> PluginMeta:
+        return PluginMeta(
+            name='tools',
+            version='1.0.0',
+            description='Tech Tools: browser-side technician utilities',
+            author='ShopDB Team',
+            dependencies=[],
+            core_version='>=0.16.0,<1.0.0',
+        )
+
+    def get_blueprint(self) -> Optional[Blueprint]:
+        # No API surface. The tools never leave the browser.
+        return None
+
+    def get_models(self) -> List[Type]:
+        # No tables. Nothing here is persisted.
+        return []
+
+    def get_navigation_items(self) -> List[dict]:
+        return [
+            {
+                'name': 'Tech Tools',
+                'icon': 'wrench',
+                'route': '/tools',
+                'position': 47,
+            },
+        ]
+
+    def on_install(self, app: Flask) -> None:
+        logger.info('Tools plugin installed')