Create a new alert rule to monitor cloud cost metrics.

Alert rules evaluate cost data against a configured condition and notify subscribers when the condition is met. Two condition types are supported:

• ANOMALY_DETECTION — Detects unusual cost changes by direction (increases, decreases, or both).
• THRESHOLDING — Triggers when an aggregated cost metric crosses a static value.

Returns the ruleID of the newly created alert rule.

Requires permission to create alert rules in the tenant. A linked report must belong to that tenant and be visible to the caller. Reports that exclude negative values or filter on their own measures cannot be linked. A missing or inaccessible report is treated as unavailable.