perf(orders): bound orders-index load with date window, pagination, and view-aware calendar (#26)

* perf(orders): default orders table to last-7/next-90-day window

* perf(orders): offset-paginate orders table at 100/page with prev/next

* perf(orders): scope calendar to visible week and load only the active view

* fix(orders): only push calendar update event in calendar view

In table mode, load_view_data does not refresh :calendar_events, so
push_event("update-calendar", ...) was firing with stale data. Guard
it behind a view_mode == "calendar" check. Also drops the unnecessary
@tag role: :staff from the pure-function calendar_window/1 unit test.

* test(orders): run perf suite async: false to avoid pool starvation

* fix(orders): preserve calendar filters and page bounds

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Co-authored-by: Shy Alter <puemos@gmail.com>

Author: timchambers