[#1217] Use the term "domain" instead of "region" to describe an election domain

[michielp1807]

Closes #1217

Inspired by Ruben's presentation today

DOD checklist

For PR maintainer

Perform these checks before marking the PR as ready:

• I have linked the PR to at least one issue.
• I assigned the PR to myself.
• I have added a description how to test this PR (see "Review Instructions").
• [For bug fixes only] I have added a regression test for the fixed bug.
• I have added documentation where necessary.

For reviewer

• I have read all code changes.
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  • locally
  • on the test environment (preferred)
• I have validated that the PR is functionally correct (use-cases, figma designs, etc.)

Review instructions

The EML's for election with multiple domains should now list a kr:ElectionDomain. The rest of the application should not behave any differently than normal.

[github-actions]

Sigrid maintainability feedback

⚠️ Your code did not improve towards your objective of 3.5 stars.

Show details

Sigrid compared your code against the baseline of 2026-09-16.

👍 What went well?

You fixed or improved 0 refactoring candidates.

👎 What could be better?

Unfortunately, 2 refactoring candidates were introduced or got worse.

Risk	System property	Location
🟠	Unit Size (Worsened)	src/models/eml/mod.rs ElectionIdentifierBuilder.try_from(ElectionConfig)
🟠	Module Coupling (Worsened)	src/core/election/macros.rs

📚 Remaining technical debt

2 refactoring candidates didn't get better or worse, but are still present in the code you touched.

View this system in Sigrid to explore your technical debt

⭐️ Sigrid ratings

System property	System on 2026-09-16	Before changes	New/changed code
Duplication	5.1	4.2	4.3
Unit Size	3.2	3.9	3.3
Unit Complexity	4.5	5.5	5.5
Unit Interfacing	2.4	5.5	5.5
Module Coupling	2.7	0.5	0.5
Component Independence	5.5	5.5	5.5
Component Entanglement	N/A	N/A	N/A
Maintainability	3.8	3.2	3.2

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[github-actions]

PDF diff summary

Template	Input	Status
model-h1	model-h1-example-1.pdf	🔵 identical
model-h1	model-h1-example-2.pdf	🔵 identical
model-h1	model-h1-example-3.pdf	🔵 identical
model-h3-1	model-h3-1-example-1.pdf	🔵 identical
model-h3-1	model-h3-1-example-2.pdf	🔵 identical
model-h3-1	model-h3-1-example-3.pdf	🔵 identical
model-h3-2	model-h3-2-example-1.pdf	🔵 identical
model-h3-2	model-h3-2-example-2.pdf	🔵 identical
model-h3-2	model-h3-2-example-3.pdf	🔵 identical
model-h4	model-h4-example-1.pdf	🔵 identical
model-h4	model-h4-example-2.pdf	🔵 identical
model-h4	model-h4-example-3.pdf	🔵 identical
model-h9	model-h9-example-1.pdf	🔵 identical
model-h9	model-h9-example-2.pdf	🔵 identical
model-h9	model-h9-example-3.pdf	🔵 identical
model-i1	model-i1-example-1.pdf	🟠 changed
model-i1	model-i1-example-2.pdf	🟠 changed
model-i4	model-i4-example-1.pdf	🔵 identical
model-i4	model-i4-example-2.pdf	🔵 identical
verzuimbrief	verzuimbrief-example-1.pdf	🔴 deleted
verzuimbrief	verzuimbrief-example-2.pdf	🔴 deleted

Download diff artifacts

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
88.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud