Add server-side column sorting to the Tickets page

[NanakiEmi]

Problem

The user Tickets page (TicketController@index) paginates with no orderBy, so tickets are shown in database insertion order. With 15 rows per page a user's most recent tickets can land on page 2, and the Reference / Type / Seat / Event columns can't be reordered.

Change

Adds server-side sorting to /tickets, mirroring the existing Admin tickets convention (same order / order_direction query params and the shared partials/_sortheader.blade.php partial):

• Sensible default order — newest event first (order=event, order_direction=desc), so recent tickets appear on page 1.
• Sortable columns — Reference, Type, Seat, Event; click a header to sort ascending/descending. Sort keys are whitelisted, so only known columns ever reach the query builder.
• Pagination preserves the sort via ->appends().
• Joins are applied only for the active sort column; ->select('tickets.*') avoids column collisions and a tickets.id tiebreaker keeps ordering deterministic. Existing eager loads and the non-admin draft filter are unchanged.

Tests

• Unit tests for TicketController@index: default order, each column ascending/descending, invalid order/direction fall back to defaults, pagination preserves the sort, and seat sort keeps unseated tickets.
• Feature test that the Tickets page renders sortable header links and rows in the requested order.
• Full suite passes; phpcs clean.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (dbcf2c2) to head (7b8dfd8).

Additional details and impacted files

@@             Coverage Diff             @@
##             develop       #72   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
- Complexity      1155      1163    +8     
===========================================
  Files            136       136           
  Lines           4053      4036   -17     
===========================================
- Hits            4053      4036   -17     

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