feat(editorconfig): configure `.editorconfig` with tabs and project rules

# feat(editorconfig): configure `.editorconfig` with tabs and project rules

| ⏱️ Estimate | 📊 Priority | 📏 Size | 📅 Start | 📅 End |
| --- | --- | --- | --- | --- |
| 1h | P1 | XS | 02-03-2026 | 02-03-2026 |

## 📸 Screenshots

| Current | Expected |
| :---: | :---: |
| | |

## 📝 Summary

- Update `.editorconfig` to use tabs instead of spaces for indentation
- Set tab width to 4 characters
- Remove `TypeScript`-specific quote rules (handled by `Prettier`/`ESLint`)
- Keep existing rules for markdown files

## 💡 Why this change?

- Project coding standards require tabs with 4-character width
- `TypeScript` quote rules should be managed by `Prettier`/`ESLint`, not `EditorConfig`
- Ensures consistent indentation across all editors and IDEs

## ✅ Benefits

- Consistent code style across the entire project
- Editor-agnostic configuration
- Separation of concerns (`EditorConfig` for basic formatting, `Prettier`/`ESLint` for advanced rules)

## 📋 Steps

### Phase 1: Update `.editorconfig`
- [x] Update `indent_style`, `indent_size` and `end_of_line`:

```diff
[*]
charset = utf-8
+end_of_line = lf
-indent_size = 2
+indent_size = 4
-indent_style = space
+indent_style = tab
insert_final_newline = true
trim_trailing_whitespace = true
```
- [x] Reorder properties in `[*]` section alphabetically:

```diff
[*]
-indent_style = tab
-indent_size = 4
charset = utf-8
end_of_line = lf
+indent_size = 4
+indent_style = tab
insert_final_newline = true
trim_trailing_whitespace = true
```
- [x] Remove `[*.ts]` section (handled by `Prettier`/`ESLint`):

```diff
-[*.ts]
-quote_type = single
-ij_typescript_use_double_quotes = false
```
- [x] Remove `max_line_length` from `[*.md]` section:

```diff
[*.md]
-max_line_length = off
trim_trailing_whitespace = false
```

## 🧪 Tests

- [x] Verify `.editorconfig` is valid
- [x] Test indentation works correctly in `VS Code`
- [x] Verify markdown files preserve trailing whitespace

## 📌 Notes

The `.editorconfig` file is read by most modern editors and IDEs to apply consistent formatting rules. This configuration ensures all developers use tabs with 4-character width regardless of their editor preferences.

## 🔗 References

### Files to modify
- `.editorconfig`

### Documentation
- https://editorconfig.org/