fix(database): use static instead of self in IsDatabaseModel

[osbre]

Problem

IsDatabaseModel trait methods using self caused two issues:

• Runtime & PHPStan: self inside a trait resolves to the class that uses the trait, not the class the method was called on. For example, calling Admin::create() (where Admin extends User and User uses the trait) built queries against User, and PHPStan incorrectly typed the return as User.
• Mago: Mago resolved self inside a trait to the trait itself (IsDatabaseModel), forcing consumers to manually narrow types with instanceof.

Fix

• Switched return types to static and routed calls through static::queryBuilder() / query(static::class).
• Inherited models now query themselves, and static analysers correctly infer the concrete model.
• Added 5 @phpstan-ignore-next-line annotations (matching the one pre-existing in resolve()).

Why the PHPStan Ignores Are Needed

QueryBuilder returns TModel|object<TModel>, but object is not generic in PHPStan - object<TModel> degrades to bare object, which doesn't satisfy static. That is what forces the suppression today.

The correct annotation (@template TModel of object with @param class-string<TModel>|TModel) resolves cleanly. But query() also accepts raw table names (e.g., query('users')), and adding |string to the union collapses PHPStan's template inference (upstream issue phpstan#12985). A permanent fix requires binding TModel from an instance rather than a class-string (similar to Eloquent), which is out of scope for this PR.

[github-actions]

Benchmark Results

Comparison of fix/database-model-static-return-types against 3.x (cf035264805564eb789f2741734e481aa3696b4d).

Open to see the benchmark results

Benchmark	Set	Mem. Peak	Time	Variability
DiscoveryScanBench(benchFullDiscoveryScan)	-	25.857mb 0.00%	19.535ms +10.69%	±0.48% -65.05%

_{Generated by phpbench against commit 5ce9c94}

[aidan-casey]

This honestly should have been static to begin with. This looks good to me, but I'll let @brendt and @innocenzi weigh in.

Thanks!

[brendt]

It wasn't static because PhpStorm had issues with traits + generics + static in the past. However, I just checked and it seems to work now with static, so let's merge!