chore: measure and start increasing jest tests coverage

[BRaimbault]

Description

Increases Jest coverage for the app's Redux logic (src/actions and src/reducers), which had almost no tests before this PR.

Tooling

• Fixed collectCoverageFrom in jest.config.js (was src/**/*.js, silently excluding all .jsx component files from coverage reports)
• Added coverage/ to .gitignore/.eslintignore/.prettierignore

Test coverage

• src/actions: 0 → 100% coverage across all 15 modules (pure action creators, no side effects)
• src/reducers: added coverage for 11 previously-untested reducers (aggregations, analyticalObject, contextMenu, dataTable, download, feature, featureProfile, interpretation, layerSources, orgUnitProfile) — all now at 100%
• src/reducers/layerEdit.js (634 lines, ~68 branches — the biggest gap, holds most of the layer-editing state logic): 3% → 100%
• src/reducers/map.js (333 lines, ~20 branches plus two internal sub-reducers): 13% → 99% (one remaining gap is dead code, marked with a TODO)

ui.js reducer is intentionally left out — another branch has in-flight changes to it.

Overall repo coverage moved from ~37% to ~42% statements (most of the codebase, src/components in particular, is still untested).

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ToDos

• Follow-up: src/components (~400 files, largely untested) is the next biggest coverage gap N/A
• Follow-up: add ui.js reducer coverage once the in-flight branch touching it lands N/A

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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 N/A
• Docs added N/A
• d2-ci dependencies replaced N/A
• Tester approved (name) N/A

[dhis2-bot]

🚀 Deployed on https://pr-3723.maps.netlify.dhis2.org

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
1 Accepted issue

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube Cloud