Add identifier column to plugins table for cleaner plugin lookup

- Added 'identifier' column (unique) for machine-readable plugin ID
- 'name' now used for display name only
- Updated trial-execution to look up by identifier first, then name
- Added migration script for existing databases

src/server/db/schema.ts

@@ -608,6 +608,7 @@ export const plugins = createTable(
     robotId: uuid("robot_id").references(() => robots.id, {
       onDelete: "cascade",
     }),
+    identifier: varchar("identifier", { length: 100 }).notNull().unique(),
     name: varchar("name", { length: 255 }).notNull(),
     version: varchar("version", { length: 50 }).notNull(),
     description: text("description"),