feat(time-series): add TS.QUERYLABELS (LABELS and VALUES forms)

[nkaradzhov]

This pull request adds client support for TS.QUERYLABELS, introduced in RedisTimeSeries 8.10. The command returns label metadata for time series matching a filter: the set of all label names (LABELS), or the set of all values of one label name (VALUES label). It completes the Grafana-style drill-down flow alongside the existing TS.QUERYINDEX.

Two methods are exposed so the mandatory label argument of the VALUES form is enforced by the signature:

• client.ts.queryLabels(filter?) → TS.QUERYLABELS LABELS [FILTER ...]
• client.ts.queryLabelValues(label, filter?) → TS.QUERYLABELS VALUES label [FILTER ...]

The command is keyless and read-only; in cluster mode the receiving shard performs the cluster-wide fan-out and returns a single merged, deduplicated reply, so clients use default keyless routing with no client-side aggregation. Filter expressions reuse the existing TS.QUERYINDEX filter representation and are sent verbatim (not parsed, reordered, or deduplicated). The reply is a flat array under RESP2 and a set under RESP3; an empty reply is a valid success.

Behavior notes:

• FILTER is optional in both forms; omitting it queries all indexed series.
• Passing an explicitly empty filter array raises a local usage error rather than silently widening to all series (a bare FILTER token is rejected by the server).
• The reply is unordered and already deduplicated; documented and tested as such.
• Not eligible for client-side caching (server advertises the dont_cache tip).

New QUERYLABELS.ts / QUERYLABELS_VALUES.ts (+ co-located specs), a shared parseQueryLabelsFilterArgument helper in helpers.ts, and registry entries with JSDoc in commands/index.ts.

🤖 Generated with Claude Code

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Note

Low Risk
Additive read-only command bindings and tests only; no changes to existing command behavior.

Overview
Adds client support for RedisTimeSeries 8.10 TS.QUERYLABELS, exposing queryLabels(filter?) (LABELS — distinct label names) and queryLabelValues(label, filter?) (VALUES — distinct values for one label). Both are keyless, read-only commands with RESP2 array / RESP3 set replies, matching the existing QUERYINDEX pattern.

Optional filters reuse the same expression style as TS.QUERYINDEX and are appended via a new shared parseQueryLabelsFilterArgument helper; an explicitly empty filter array throws locally instead of widening to all series. Registry entries and integration tests cover argument encoding, filtered/unfiltered queries, empty results, and RESP2.

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