feat(meta): typed meta as attributes of the Pollora models

[ogorzalka]

Second half of phase 2 of « Pollora — Meta typées : document d'implémentation ». Stacked on #399 (base feature/meta-owners; GitHub retargets it to develop once #399 is merged and its branch deleted).

class Event extends \Pollora\Models\Post
{
    protected $postType = 'event';
}

$event = Post::find($id);              // an Event: bound to 'event' at discovery
$event->capacity;                      // int (or by key: $event->sold_out)
$event->capacity = 'many';             // InvalidMetaValueException, now
$event->capacity = 250;
$event->save();                        // update_metadata(): sanitize, hooks, cache
Event::whereMeta('capacity', '>=', 100)->get();

User::find(1)->newsletterOptIn;        // #[UserMeta] on the user model

Design

• HasTypedMeta is on Pollora\Models\Post, Page, Term, User and Comment (as the document puts it, so $user->newsletter_opt_in works on the authenticated user). getAttribute()/setAttribute() intercept only names a schema of the object type declares (MetaSchemaRepository::declares(), an O(1) index), then find the schema for the object's subtype: post_type column or $postType for posts, the taxonomy relation for terms, none for users and comments. Everything else goes to Colt/Eloquent untouched.
• Writes are checked by MetaValueCaster::toStorage() immediately, kept out of the model's attributes, and written by the saved event through a MetaRecord (so a new model gets its ID first).
• No behaviour change without typed meta. A class is "known to carry typed meta" when the repository has schemas for its object type and static subtype ($postType; users/comments: any #[UserMeta]/#[CommentMeta]). Only then does it drop meta from $with; each model it loads joins a batch on retrieved, and the first typed read primes the whole batch with one update_meta_cache() call. (A first version overrode newCollection(), whose generic return type PHPStan could not reconcile with Colt's models in CI.) The generic Post keeps eager loading. Undeclared keys keep Colt's fallback (lazy relation).
• whereMeta(): CAST(meta_value AS SIGNED) / DECIMAL(65, 10) for numbers, stored-form comparison otherwise (dates are stored in UTC with a fixed format, so they sort as strings); null means the meta is absent. Operators are whitelisted (they are concatenated into the raw SQL).
• Post::registerPostType(): MetaDiscovery also keeps classes extending a Colt post model and binds their $postType default.
• Rector's ScalarParamTypeByMethodCallTypeRector is skipped for the trait: typing $key breaks compatibility with Eloquent's untyped getAttribute($key) (fatal).

Verified on pollora-test, temporary classes and values since removed

#[PostMeta('post')] (int $tmpViews, ?string $tmpSubtitle), class Article extends Post { $postType = 'post' }, #[UserMeta]:

• Post::find() returns App\Cms\TmpMeta\Article.
• A collection read with ->tmpViews on each: 1 Eloquent query + 1 wpdb query (meta cache), integers; measured again after the batch rework: 20 posts, 1 wpdb query.
• $article->tmpViews = 999; ->tmpSubtitle = 'Typé'; ->save() → get_post_meta() returns them; 'many' throws.
• whereMeta('tmpViews', '>=', 300) and whereMeta('tmpSubtitle', null) return the right IDs on MySQL.
• User::find(1)->tmpNewsletterOptIn: false, then true after save().
• An undeclared key (_edit_lock) still reads through Colt on a typed model.

Tests

HasTypedMetaTest (reads by property and key, generic post model, untouched attributes, checked writes and save, defaults before save, user meta, $with, cache priming, whereMeta() SQL), repository forObject()/declares(), discovery binding. Full suite 1648 passed; Pint, PHPStan, Rector clean.