Trim README to the essentials

Drop the config table, per-column schema notes and expanded id-format
explanation; keep setup steps, the endpoint list and the id note.

README.md

@@ -1,82 +1,28 @@
 # Student Management System (MW600)
 
-A mini system for managing student records, built with **Express** and **MySQL**.
+Student records CRUD mini system — Express + MySQL, single-file backend
-
+(`server.js`) with a plain HTML frontend (`index.html`).
-Backend is a single file (`server.js`) exposing a CRUD API; the frontend is a
-plain HTML page (`index.html`) served from the same server.
-
-## Requirements
-
-- Node.js 20.6+ (uses `process.loadEnvFile`)
-- A running MySQL server
 
 ## Setup
 
 ```sh
 npm install
-cp .env.example .env      # then fill in your MySQL credentials
+cp .env.example .env    # fill in your MySQL credentials
 npm run db:push         # creates the database and imports student_db.sql
 npm start
 ```
 
-Open http://localhost:3000
+Then open http://localhost:3000
-
-`npm run db:push` creates the `student_db` database and imports the schema and
-seed data from `student_db.sql`. It is safe to re-run — the script drops and
-recreates the `students` table.
-
-## Database
-
-`student_db.sql` holds the schema and seed rows for a single table:
-
-| Column       | Type         | Notes                        |
-| ------------ | ------------ | ---------------------------- |
-| `id`         | `INT`        | Primary key, assigned by app |
-| `name`       | `VARCHAR(100)` | Required                   |
-| `course`     | `VARCHAR(50)`  | Required                   |
-| `year_level` | `INT`        | Required, 1–6              |
-
-### ID format
-
-Ids are **8 digits**: a 2-digit year followed by a 6-digit counter that resets
-each year.
-
-```
-26 000001   -> first student added in 2026
-26 000002   -> second student added in 2026
-27 000001   -> first student added in 2027
-```
-
-The counter is per year, so ids never collide across years. Because MySQL cannot
-generate this pattern, `id` has no `AUTO_INCREMENT` — the application assigns it.
-Allocation is guarded by a MySQL advisory lock (`GET_LOCK`) so simultaneous
-requests cannot receive the same id.
 
 ## API
 
-| Method   | Path                 | Response                                     |
+| Method   | Path                | Description   |
-| -------- | -------------------- | -------------------------------------------- |
+| -------- | ------------------- | ------------- |
-| `GET`    | `/api/students`      | `200` list of students                       |
+| `GET`    | `/api/students`     | list students |
-| `GET`    | `/api/students/:id`  | `200` student, `400` bad id, `404` not found |
+| `GET`    | `/api/students/:id` | one student   |
-| `POST`   | `/api/students`      | `201` created, `400` invalid, `415` not JSON |
+| `POST`   | `/api/students`     | create        |
-| `PUT`    | `/api/students/:id`  | `200` updated, `400` invalid, `404` not found |
+| `PUT`    | `/api/students/:id` | update        |
-| `DELETE` | `/api/students/:id`  | `204` deleted, `404` not found               |
+| `DELETE` | `/api/students/:id` | delete        |
 
-Errors use one envelope:
+Ids are 8 digits: a 2-digit year plus a 6-digit counter that resets each year,
-
+so the first student added in 2026 is `26000001`.
-```json
-{ "error": { "code": "VALIDATION_ERROR", "message": "...", "details": [] } }
-```
-
-## Configuration
-
-All connection settings live in `.env` (not committed):
-
-| Variable      | Default       |
-| ------------- | ------------- |
-| `DB_HOST`     | `127.0.0.1`   |
-| `DB_PORT`     | `3306`        |
-| `DB_USER`     | `root`        |
-| `DB_PASSWORD` | *required*    |
-| `DB_NAME`     | `student_db`  |
-| `PORT`        | `3000`        |