[Bug]: json_decode coerces numeric string attributes to integers

[mhortulanus]

### PHP Version
8.4.19

### Version
2.1.0

### Bug Description

When `setContent()` receives a string that contains only digits (e.g. `"42"`), `getContentType()` misidentifies it as JSON because `json_decode("42")` is valid JSON. This causes the document to be set to an integer instead of being parsed as HTML text content.

The issue is in `getContentType()` (Editor.php:89–101): it checks if `json_decode` succeeds, but bare numbers, booleans, and `null` are all valid JSON scalars — so any numeric string passes the JSON check.

### Steps to Reproduce

```php
$editor = new \Tiptap\Editor();
$editor->setContent("42");

$doc = $editor->getDocument();
// Expected: parsed HTML document with text "42"
// Actual: int(42)

Expected Behavior

A plain numeric string like "42" should be treated as HTML content and parsed into a proper tiptap document node.

Actual Behavior

The string is identified as JSON, json_decode("42", true) returns int(42), and the document becomes an integer.

Suggested Fix

In getContentType(), after json_decode succeeds, verify the result is actually a valid tiptap document structure (an array with a type key):

$decoded = json_decode($value, true, 512, JSON_THROW_ON_ERROR);

if (is_array($decoded) && isset($decoded['type'])) {
    return 'JSON';
}

return 'HTML';

Expected Behavior (Detailed)

A plain numeric string like "42" passed to setContent() should be treated as HTML content, resulting in a valid tiptap document structure:

$editor = new \Tiptap\Editor();
$editor->setContent("42");

$doc = $editor->getDocument();

// Expected:
// [
//     "type" => "doc",
//     "content" => [
//         [
//             "type" => "paragraph",
//             "content" => [
//                 ["type" => "text", "text" => "42"]
//             ]
//         ]
//     ]
// ]

Additional Context (Optional)

Filament v4 usage.

Dependency Updates

• Yes, I've updated all my dependencies.

[iindex]

faced the same issue.
Alongside would prefer to have separate methods to state the content, like:

    public function setHTML(string $value): self
    {
        $this->document = (new \Tiptap\Core\DOMParser($this->schema))->process($value);
        $this->document = $this->schema->apply($this->document);
        return $this;
    }

Or a second optional parameter:

    public function setContent($value, $contentType = null): self
    {
        $contentType ??= $this->getContentType($value);
        if ($contentType === 'HTML') {
            $this->document = (new DOMParser($this->schema))->process($value);
        }