Test coverage: stores at 100% (uiStore + chatStore)

[hh54188]

Summary

• Achieved 100% line/function/branch coverage for store files (src/stores/**/*.js).
• Addressed the last uncovered line in src/stores/uiStore.js (setter for testModalVisible).

What changed

• Updated src/tests/stores/uiStore.test.js to include comprehensive tests for setTestModalVisible and included assertions for testModalVisible in the resetUIState flow.
• Verified coverage with npm run test:stores:coverage which reports 100% across uiStore.js and chatStore.js.

Evidence

• Local run in the GitHub Actions runner:

% Coverage report from v8
--------------|---------|----------|---------|---------|-------------------
All files     |     100 |      100 |     100 |     100 |
 chatStore.js |     100 |      100 |     100 |     100 |
 uiStore.js   |     100 |      100 |     100 |     100 |
--------------|---------|----------|---------|---------|-------------------

Reasoning

• The uncovered analysis (uncovered-analysis.json) identified line 86 in src/stores/uiStore.js as uncovered: state.testModalVisible = visible;.
• Existing tests covered all other modal setters; we followed the established pattern to add symmetrical tests for the test modal.
• We also asserted that resetUIState resets testModalVisible to false to exercise that path.

How to validate

1. Run npm ci (if needed) and ensure vitest is available.
2. Execute npm run test:stores:coverage.
3. Confirm coverage results are 100% for stores.

Notes

• No production code changes; tests only.
• No new files added; only modified existing test file per requirements.