docs: add technical documentations

* add flutter-architecture.md

* add guildlines/conventional-commit.md

*add database-schema.md

Author: tqha1011

documentation/architecture/database-schema.md

@@ -0,0 +1,19 @@
+## Database Schema
+
+The database is built on **PostgreSQL** (hosted via Supabase) and is strictly secured using **Row Level Security (RLS)**.
+
+
+
+### Core Database Dictionary
+
+| Table Name | Description / Purpose | Key Relationships & Security |
+| :--- | :--- | :--- |
+| **`profile`** | Extended data for Supabase users (username, avatar, timezone). | `1:1` with `auth.users`. |
+| **`category`** | Life contexts or folders created by users (e.g., Work, Health). | Belongs to `profile` (RLS enforced). |
+| **`task`** | The main entity containing to-do properties (title, status, priority). | Belongs to `profile` and `category`. |
+| **`note`** | Satellite table for long-form text descriptions. | `1:N` with `task`. |
+| **`subtask`** | Satellite table acting as a checklist inside a specific task. | `1:N` with `task`. |
+| **`reminder`** | Scheduling entity for push notifications. | `1:N` with `task`. |
+
+### Security Architecture
+* **Row Level Security (RLS):** Every core table contains a `profile_id`. RLS policies are enforced at the database level so users can only `SELECT`, `INSERT`, `UPDATE`, or `DELETE` their own data.

documentation/architecture/flutter-architecture.md

@@ -0,0 +1,40 @@
+
+# Flutter App Architecture
+
+**TaskManagement App** is built based on **Feature-Based MVVM**
+Architecture
+
+In each feature, we organize the folders based on **MVVM** Architecture
+
+### 1. core
+- `.env`: Contains **Supabase URL** and secrets key
+- **Themes & Constants**: Stores global UI configurations and constant values.
+
+### 2. features
+- `model`: Contains classes to define data
+- `view`: Contains UI widgets
+- `viewmodel`: Implements business logic and handles state management.
+- `services`: Handles data operations and communicates with the Supabase Backend.
+```plaintext
+.
+└── 📂 src/
+    ├── 📂 android
+    ├── 📂 ios
+    ├── 📂 lib/
+    │   ├── 📂 core
+    │   ├── 📂 features/
+    │   │   ├── 📂 auth/
+    │   │   │   ├── 📂 model
+    │   │   │   ├── 📂 view
+    │   │   │   ├── 📂 viewmodel
+    │   │   │   └── 📂 services
+    │   │   └── 📂 ...
+    │   └── main.dart
+    ├── 📂 test
+    ├── pubspec.lock
+    ├── pubspec.yaml
+    └── .metadata
+
+```
+
+

documentation/guildlines/conventional-commit.md

@@ -0,0 +1,24 @@
+## 📌 Git Commit Convention
+
+To maintain a clean, readable, and trackable commit history, all team members **MUST** adhere to the following commit guidelines.
+
+### 1. Standard Syntax
+`<type>(<scope>): <short_description>`
+
+### 2. Allowed Types
+
+| Icon | Type | Description | Example |
+| :---: | :--- | :--- | :--- |
+| ✨ | **feat** | Adds a new feature to the application. | `feat(auth): add JWT login API` |
+| 🐛 | **fix** | Patches a bug or resolves an issue. | `fix(cart): resolve incorrect total price calculation` |
+| ♻️ | **refactor**| Restructures code without changing existing logic or adding features. | `refactor(product): clean up IProductService interface` |
+| 📝 | **docs** | Adds or updates documentation (README, diagrams, etc.). | `docs(ci): update SonarCloud workflow` |
+| 🔧 | **chore** | Maintenance tasks, configurations, or dependency updates. | `chore(deps): bump Newtonsoft.Json to 10.0.4` |
+| 🚀 | **perf** | Code changes that improve performance. | `perf(db): add index to Product table for faster queries` |
+
+### 3. Golden Rules
+- The `type` and `scope` MUST strictly be in **lowercase**.
+- The description must be clear, concise, and straight to the point.
+- **NEVER** push code with meaningless commit messages such as: `update`, `fix bug`, `done part A`, `asdfgh`.
+
+Reference: [Conventional Commit](https://www.conventionalcommits.org/en/v1.0.0/)