refactor(studio): extract pure helpers to src/util.js (step 2)

[byrongamatos]

What

Step 2 of the studio migration. Moves 9 state-free helpers out of the IIFE into src/util.js:

_parseTimeInput, _formatTime, _formatDate, _esc, Path_stem, _eqLabel, _compLabel, _polarToCartesian, _describeArc

main.js imports them by the same names, so call sites are unchanged. Adds package.json (type:module, npm test) so the reusable CI runs the new tests/util.test.mjs real-import tests. main.js 2856 → 2799. Move-only, no behaviour change.

Tests

node --test 7/7, pytest 25/25 (backend unaffected). Codex preflight: 0.

Summary by CodeRabbit

• New Features
  • Improved time entry support (e.g., M:SS with optional milliseconds) and consistent time display formatting.
  • More reliable, user-friendly date formatting.
• Bug Fixes
  • Strengthened HTML escaping for safer interpolation.
  • More consistent filename stem handling, EQ/comp label summaries, and SVG arc geometry used in the interface.
• Tests
  • Added automated coverage for parsing/formatting, escaping, path handling, and geometry helpers.
  • Tests can now be run via the standard Node test command.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: fc274749-0136-4bbe-8016-3ca97ee40cee

📥 Commits

Reviewing files that changed from the base of the PR and between 8219625 and fc2a2f2.

📒 Files selected for processing (2)

• package.json
• src/util.js

🚧 Files skipped from review as they are similar to previous changes (2)

• package.json
• src/util.js

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📝 Walkthrough

Walkthrough

This PR extracts several state-free helper functions from src/main.js into src/util.js, updates main.js to import them, adds tests/util.test.mjs, a package.json test script, and a CHANGELOG entry.

Changes

Utility extraction cohort

Layer / File(s)	Summary
New util.js helper module src/util.js	Adds exported pure functions for time parsing/formatting, date formatting, HTML escaping, path stem extraction, EQ/comp labeling, and SVG arc geometry helpers.
main.js imports replace local helper definitions src/main.js	Imports the helpers from ./util.js and removes the corresponding local function definitions at their former locations.
Tests, test tooling, and changelog tests/util.test.mjs, package.json, CHANGELOG.md	Adds a Node test-runner suite for the new helpers, a package.json test script, and a CHANGELOG entry describing the move-only refactor.

Estimated code review effort: 2 (Simple) | ~12 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: extracting pure studio helpers into src/util.js as a step-2 refactor.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/es-module-split-util

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[Copilot]

Pull request overview

This PR continues the Studio ES-module migration by extracting a set of pure, state-free helper functions from src/main.js into a dedicated src/util.js module, then validating the new module via real ES-module imports using Node’s built-in test runner.

Changes:

• Added src/util.js exporting nine pure helpers, keeping the original names to preserve existing call sites.
• Updated src/main.js to import the extracted helpers and removed the inlined helper implementations.
• Added Node test coverage for the helpers (tests/util.test.mjs) and introduced a minimal package.json to run those tests via npm test.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/util.test.mjs	Adds Node node:test coverage for the extracted utility helpers via real ESM import.
src/util.js	New module containing extracted pure helpers (exported under existing names).
src/main.js	Imports helpers from ./util.js and removes their previous in-file definitions.
package.json	Introduces ESM mode and an npm test script to run Node tests.
CHANGELOG.md	Documents migration step 2 and the new test/CI entrypoints.

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