feat(client): list_orders updated_since filter

[dougborg]

Problem

Incremental sync workflows (Katana → StatusPro reconciliation, change-tracking dashboards, "what moved overnight" reports) need a "show me everything that changed since last sync" filter. Today the only time-based knobs on list_orders are due_date_from / due_date_to, which is a different axis (when the order is due, not when it was last updated).

Proposed shape

GET /orders?updated_since=2025-01-01T00:00:00Z

Returns orders whose server-tracked updated_at (or equivalent) is >= the given ISO 8601 timestamp.

Open questions

• Does the server already track an updated_at per order? Probe in area/spec: investigate StatusPro server capabilities for filter additions #30.
• What counts as an "update"? Status change, comment add, due-date change, all of the above? Should match the server's existing semantics — don't invent.

Acceptance

• OpenAPI spec adds updated_since query parameter to GET /orders
• Generated client supports it
• Orders.list(updated_since=…) helper kwarg
• MCP list_orders tool exposes it
• Test verifying orders with updated_at before the boundary are excluded
• Help resource updated

Depends on

• area/spec: decide spec ownership model and execute #29 (F2) — spec ownership
• area/spec: investigate StatusPro server capabilities for filter additions #30 (F3) — server-capability probe

Tracking

Part of epic #31, Tier 1.

[dougborg]

Update from #30 probes (2026-04-29)

The server silently ignores every name we tried: updated_since, since, modified_since. All return baseline's 478 — including the alarming case updated_since=2020-01-01 returning the same count as updated_since=2026-04-29. Definitely not respected.

Worse: GET /orders/{id} does not even expose an updated_at field at the top level, so the server may not be tracking it visibly. Adding the filter would require the server to start tracking and exposing updated_at before exposing it in the query.

Re-scope: Upstream feature request. No client-side workaround possible — incremental sync is fundamentally a server-side capability.