feat: Phase 3 campaign management

Campaign CRUD API with cascading delete across all campaign-scoped
tables, a systems endpoint to seed the create-campaign form, active
campaign state wired to the sidebar chaos factor, and a campaign
management view for creating/switching/deleting campaigns.

server/index.js

@@ -8,6 +8,7 @@ const threadsRouter = require('./routes/threads');
 const npcsRouter = require('./routes/npcs');
 const notesRouter = require('./routes/notes');
 const tablesRouter = require('./routes/tables');
+const systemsRouter = require('./routes/systems');
 
 const app = express();
 const PORT = 4000;
@@ -25,6 +26,7 @@ app.use('/api/threads', threadsRouter);
 app.use('/api/npcs', npcsRouter);
 app.use('/api/notes', notesRouter);
 app.use('/api/tables', tablesRouter);
+app.use('/api/systems', systemsRouter);
 
 app.listen(PORT, () => {
   console.log(`Mythic Oracle running at http://localhost:${PORT}`);