feat: add Combined (multilayer) data table [superseded]

[BRaimbault]

Implements DHIS2-20543

Description

Adds the Combined data table — a new view that joins multiple map layers into a single table, keyed off a reference org-unit layer, instead of viewing one layer's data at a time.

• Reference org units are picked via a dedicated layer-edit dialog; other open layers join against them by org unit, parent org unit, or spatial containment.
• Per-layer join columns adapt to layer type: numeric/aggregated values for Thematic/Earth Engine, and value/count/category columns for Facility, OrgUnit, Event, and Tracked Entity layers, with a Count/Percentage toggle for categorical joins.
• Column picker, pinning, sorting, filtering, global search, and row selection/hover all work the same way as the existing single-layer table, and selection stays in sync with the map (including cross-layer highlighting).
• Context menu support for zoom-to-feature; join and column configuration persist on the reference layer and survive save/reload.

The rest of the branch is stack cleanup carried along from earlier PRs in this series: data table filter/sort/selection consistency fixes, hidden technical columns, a handful of Combined-table persistence and join-parity fixes found in review, and a duplicate-API-call performance pass (org unit names, option sets, and Event layer reloads were being fetched more than once).

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Quality checklist

Add N/A to items that are not applicable.

• Dashboard tested N/A
• Cypress and/or Jest tests added/updated
• Docs added
• d2-ci dependencies replaced N/A
• Tester approved (name)

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Screenshots

supporting images

[dhis2-bot]

🚀 Deployed on https://pr-3741.maps.netlify.dhis2.org

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
4.1% Duplication on New Code

See analysis details on SonarQube Cloud