feat(runpanelquery): run Infinity panels through /api/ds/query

[arunms-ziwo]

What

run_panel_query now executes panels on the Infinity datasource (yesoreyeram-infinity-datasource). Infinity targets are structured (url, root_selector, parser, headers, inline data) and the plugin backend runs them for the backend parsers, so the target is sent to /api/ds/query as saved, with template variables substituted in every string field, the same way CloudWatch panels are executed. Panels using the default simple parser (browser-side) are refused with a message naming the parser to change; backend, uql, groq and jq-backend are accepted.

• normalizeDatasourceType maps the plugin ID to infinity.
• extractPanelInfo accepts an empty query expression for structured targets (CloudWatch and Infinity share one helper).
• executeInfinityPanelQuery, routed from the datasource switch; empty-result hints for the URL and root_selector.
• Tool description and README mention Infinity with a backend parser.

Why

Dashboards that read inventory or CMDB systems (NetBox and similar JSON APIs) through Infinity could not be executed with variable overrides; the tool answered "datasource type is not supported by run_panel_query".

Tiering

No new tool or parameter: one more datasource type behind the existing run_panel_query, gated by the same runpanelquery category. The tool description grows by a few words.

Tests

Unit tests (//go:build unit) for type normalisation, target extraction, the /api/ds/query payload (datasource, parser, substituted url and root_selector, time range), the parser gate and a nil target. go vet, gofmt, make lint-jsonschema lint-openapi and go test -tags unit ./tools pass locally.

[cla-assistant]

All committers have signed the CLA.

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 2 potential issues.

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[arunms-ziwo]

Both Bugbot findings addressed in the follow-up commit: the parser gate now accepts only backend and jq-backend (matching the plugin's isBackendQuery), refusing UQL and GROQ like simple; extractPanelInfoV2 uses the shared usesStructuredTarget check so v2 Infinity panels reach the executor, with a test for the v2 path.