refactor: migrate to monorepo structure with Docker, PocketBase, and e2e tests

- Reorganize into apps/, packages/, docs/, e2e/, pocketbase/ directories
- Add Dockerfiles for web, worker, and PocketBase services
- Add docker-compose.yml for local orchestration
- Add turbo.json for monorepo task management
- Add Playwright e2e test infrastructure
- Add PocketBase backend with migrations
- Remove Vite/Next.js/ESLint/PostCSS config files
- Update package.json with workspace dependencies
- Add .env.example and .dockerignore

pocketbase/pb_migrations/1700000011_create_task_attachments.js

@@ -0,0 +1,45 @@
+module.exports = {
+  up: async (app) => {
+    const collection = new app.models.Collection({
+      name: 'task_attachments',
+      type: 'base',
+      schema: app.models.NewSchema([
+        app.models.NewSchemaField({
+          name: 'task_id',
+          type: 'relation',
+          required: true,
+          options: { collectionId: 'tasks', maxSelect: 1, cascadeDelete: true }
+        }),
+        app.models.NewSchemaField({
+          name: 'file',
+          type: 'file',
+          required: true,
+          options: { maxSelect: 1, maxSize: 5242880, mimeTypes: [] }
+        }),
+        app.models.NewSchemaField({
+          name: 'filename',
+          type: 'text',
+          options: { maxSize: 255 }
+        }),
+        app.models.NewSchemaField({
+          name: 'mime_type',
+          type: 'text',
+          options: { maxSize: 255 }
+        }),
+        app.models.NewSchemaField({
+          name: 'size',
+          type: 'number',
+          options: { min: 0 }
+        })
+      ]),
+      indexes: [
+        'CREATE INDEX idx_task_attachments_task_id ON task_attachments (task_id)'
+      ]
+    });
+    return app.save(collection);
+  },
+  down: async (app) => {
+    const collection = await app.findCollectionByNameOrId('task_attachments');
+    return app.delete(collection);
+  }
+};