Add a stored normalized name column with an index

[git-hyagi]

Add a name_normalized field to PythonPackageContent that stores the pre-computed LOWER(REGEXP_REPLACE(name, ...)) value, populated via a BEFORE_SAVE hook.
Add db_index=True.
Change all name__normalize= lookups to use name_normalized__exact=. This eliminates the regex computation at query time.

closes: #1159
Assisted By: claude-opus-4.6

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[gerrod3]

Thanks!

[jobselko]

Partial review - I will look at viewsets.py tomorrow.

[jobselko]

Why was name changed to name_normalized and why was name_normalized added to distinct?

[git-hyagi]

Why was name changed to name_normalized

now that we have a name_normalized field, we can use it to do a "better ordering" (instead of ordering Django, django, and DJANGO as different entries and in different order, we can now handle them as a "same" entrance during ordering).

why was name_normalized added to distinct?

https://docs.djangoproject.com/en/5.2/ref/models/querysets/#django.db.models.query.QuerySet.distinct

"On PostgreSQL only, you can pass positional arguments (*fields) in order to specify the names of fields to which the DISTINCT should apply. [..]For a normal distinct() call, the database compares each field in each row when determining which rows are distinct. For a distinct() call with specified field names, the database will only compare the specified field names."

"When you specify field names, you must provide an order_by() in the QuerySet, and the fields in order_by() must start with the fields in distinct(), in the same order." (order_by and distinct fields must match)