feat(plugins): fire domain hooks from ticket + assignment services

[mpge]

Follow-up to #96. That PR landed the plugin hook dispatch mechanism and the activation lifecycle hooks; this one wires the dispatch into the core ticket write paths so registered plugins actually fire end-to-end during real ticket operations.

Actions dispatched

From Escalated.Services.TicketService:

• ticket_created — on create
• ticket_replied / internal_note_added — on reply (by is_internal)
• ticket_status_changed, plus ticket_resolved / ticket_closed / ticket_reopened — on status transition
• ticket_priority_changed — on priority change

From Escalated.Services.AssignmentService:

• ticket_assigned / ticket_unassigned

Filters applied

In TicketService.list/1:

• ticket_list_query — the Ecto query before execution
• ticket_list_data — the loaded ticket list

Hook names mirror the Laravel HookRegistry (unprefixed here, since the Escalated.Plugins namespace already scopes them). Dispatch runs after each write commits and is failure-isolated — a raising plugin is logged and skipped, never breaking a ticket operation.

Notes

• Adds an integration test (ticket_service_hooks_test.exs) that activates a capturing plugin and asserts the real service calls fire ticket_created, ticket_status_changed + ticket_resolved, ticket_replied / internal_note_added, and that a ticket_list_data filter transforms list/1 output.
• Reflows a few pre-existing over-length lines that mix format rewraps now the files are touched, and alphabetizes one alias group (both surfaced by CI's PR-scoped format/credo checks).
• The Escalated.Plugins.Hooks moduledoc now lists the hooks the core services dispatch.

Verification

Ran the exact CI toolchain (Elixir 1.15 / OTP 26) in a container: mix format --check-formatted clean, mix credo --strict no issues, mix test 548 tests, 0 failures.