perf(server): scope refreshIdeas status queries

[kvnloo]

Problem

refreshIdeas() performs three full-table reads and then filters by status in JavaScript:

• all tasks → status === "succeeded"
• all ideas → status === "new"
• all goals → status === "active"

Terminal task history is retained, so the task scan grows without bound and runs on both maintenance refreshes and on-demand idea refreshes.

A downstream PGlite benchmark measured the largest hotspot (2,000 ~2KB tasks) at roughly:

• full task list + filter: ~423.6ms / ~3.0MB
• status-scoped query: ~17.7ms

Change

Add Store.listByStatus() with the same updated_at DESC,id ordering as list(), then use it for those three status predicates only.

All remaining filters and side effects stay unchanged:

• messageId checks;
• obsolete idea CAS;
• empty-milestone goal check;
• mail/sent dedupe;
• final full ideas return.

Regression

Persistence coverage compares the scoped query directly with the previous list().filter(item.status === value) semantics and verifies owner/kind isolation.

No idea ranking, task lifecycle, or goal behavior changes.