CNS-138: console: distinct query history empty state when statement logging sampling is off

[jubrad]

https://linear.app/materializeinc/issue/CNS-138/console-distinct-empty-state-when-the-statement-logging-sample-rate-is

Problem

Query history is backed by statement logging, which an operator can turn off by setting the sample rate to 0. When that happens the console showed the generic filter-oriented "No results found." state, so the user could not tell sampling was off from their filters being too narrow.

Solution

• New API module console/src/api/materialize/query-history/statementLoggingMaxSampleRate.ts reads SHOW statement_logging_max_sample_rate, following the existing maxReplicasPerCluster.ts pattern. The effective rate is min(session statement_logging_sample_rate, system statement_logging_max_sample_rate), so the cap alone detects a hard opt-out.
• QueryHistoryList renders a distinct SamplingDisabledState when the result set is empty and the cap is 0, naming both ways to raise it: ALTER SYSTEM SET statement_logging_max_sample_rate, and the Materialize operator's Helm chart values for self-managed. The filter-oriented state is unchanged for a non-zero rate.

The new query is gated on enabled: isEmpty, so it never runs on the path that renders rows.

Testing

Snapshot test for the compiled query, plus two cases in QueryHistoryList.test.tsx covering both empty-state branches.

While adding them I found DEFAULT_FETCH_QUERY_LIST_HANDLER never matched anything: the schema defaults dateRange to a window ending at new Date(), so its separate queryHistoryListSchema.parse(...) produced different filters than the PARSED_DEFAULT_SCHEMA_VALUES the component renders with. The handler now reuses the same parsed value.

Notes for the reviewer

• Rebased onto main now that CNS-137: un-gate the query history view in self-managed console builds #38407 (CNS-137) has landed. This branch previously carried a cherry-pick of @leedqin's console: Enable query history for self managed #36533 un-gate; main has that change already, so the duplicate commit was dropped in the rebase. console: Enable query history for self managed #36533 is now redundant and can be closed.
• The Helm chart value the copy alludes to comes from CNS-136: expose statement logging sample rate in the operator chart #38406 (CNS-136). The message deliberately names no specific chart key, so it stays accurate regardless of what that PR settles on.
• The copy renders in both deployment modes and mentions Helm only in a self-managed-qualified sentence, rather than branching on AppConfigSwitch.

🤖 Generated with Claude Code

[leedqin]

Also have a PR for this : #36533

[leedqin]

LGTM!