Add internal GET endpoint for global_config keys

Allows other services (e.g. room-planner) to read shared config
stored in settings_db without cross-database queries. Auth via
SETTINGS_SECRET bearer token, same pattern as /internal/integration.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/routes/integrations.js

@@ -159,6 +159,18 @@ export async function integrationRoutes(app) {
     return value
   })
 
+  // GET /settings/api/internal/global-config/:key — service-to-service read of global_config
+  // Authenticated by SETTINGS_SECRET bearer token; returns the value JSON for the given key.
+  app.get('/internal/global-config/:key', async (req, reply) => {
+    const token = (req.headers.authorization || '').replace(/^Bearer\s+/i, '')
+    if (!token || token !== process.env.SETTINGS_SECRET) {
+      return reply.status(401).send({ error: 'Unauthorized' })
+    }
+    const { rows: [row] } = await pool.query('SELECT value FROM global_config WHERE key = $1', [req.params.key])
+    if (!row) return reply.status(404).send({ error: 'Not found' })
+    return { value: row.value }
+  })
+
   // GET /settings/api/internal/integration/:slug — service-to-service, no user session required
   // Authenticated by SETTINGS_SECRET bearer token; returns unmasked credentials.
   app.get('/internal/integration/:slug', async (req, reply) => {