Refuse names that differ only in case in lint:structure

[olehwebdev]

What and why

The 0.4.0 Release workflow failed to build the installers on macOS and Windows (run 14):

[MISSING_EXPORT] "ActionFields" is not exported by ".../RuleForm/ActionFields.ts".

ActionFields.tsx sat beside actionFields.ts, and RuleNotes.tsx beside ruleNotes.ts. macOS and Windows ignore case, so import './ActionFields' found actionFields.ts first. CI builds only on Linux, so nothing caught it until the release. olehwebdev/console-editor#27 fixes those two pairs. This PR stops the mistake from coming back.

npm run lint:structure now also walks src, scripts and test and refuses, within one folder:

• two names that differ only in case (Logo.svg, logo.svg). These can't even coexist in a checkout on macOS or Windows.
• two modules an import without an extension reaches by names that differ only in case. A module is a folder, or a file with one of Vite's resolve.extensions (.mjs .js .mts .ts .jsx .tsx .json). Examples: ActionFields.tsx beside actionFields.ts, or a folder foo/ beside Foo.ts.

It passes:

• Markdown.tsx beside markdown.css: a stylesheet is imported by its whole name, so the two never meet.
• Names spelled alike (Foo.ts beside Foo.tsx): no case is involved, so every file system treats them the same.

The check runs wherever lint:structure already does: CI, the pre-push hook, and the agents' stop hook. It needs no new wiring.

Code:

• scripts/structure/:
  • caseClashes.ts: the pure check for one folder's entries;
  • lookupNames.ts: the names a lookup reaches an entry by;
  • findCaseClashes.ts: the walk;
  • constants.ts: the checked roots and module extensions.
• check-structure.ts adds the walk's findings to its report.

Docs: CLAUDE.md and CONTRIBUTING (the rule, and the lint:structure comment), the SPEC's test table, and the code-structure skill's naming step.

The branch also carries #27's rename commit (8acf75a, the same change). Without it, lint:structure would fail on main, which still has both pairs. Git merges the identical rename cleanly, whichever PR merges first.

How it was tested

• On main's tree, before the rename, npm run lint:structure reports exactly the two pairs:

  src/renderer/src/features/rule/edit/ui/RuleForm  no case clashes: ActionFields.tsx, actionFields.ts: macOS and Windows ignore case, so they take one for the other (an import may load the wrong one): rename one
  src/renderer/src/features/rule/edit/ui/RuleForm  no case clashes: RuleNotes.tsx, ruleNotes.ts: …
  

  With the rename it passes (Code structure: 2238 files OK.).
• New unit tests in test/unit/checkStructure.test.ts:
  • the release's clashing pairs fail, and so do a folder beside a module and .json beside .js;
  • two non-module names that differ only in case fail, reported once;
  • the stylesheet case, names spelled alike, and the renamed files pass;
  • a temporary tree is walked: clashes in src and test are named by folder, docs/ is ignored, and the tree passes once they're removed.
• Checks: npm run typecheck, lint:fsd, lint:structure, lint, lint:unused, lint:duplicates and lint:secrets pass.
• Tests: npm test passes (1,175). xvfb-run -a npm run test:e2e passes (109).
  • The first end-to-end run had one timing failure, in inspect.e2e.test.ts › "opens the original read-only…": a poll with vitest's default 1-second timeout, waiting for the bundle to open.
  • That test is untouched here. It passed 3 of 3 on its own and in a full rerun.

Checklist

• Comes from a git flow branch (feature/…, bugfix/…) into main, and does one thing
• npm run typecheck, npm run lint:fsd, npm run lint:structure, npm run lint, npm run lint:unused, npm run lint:duplicates, npm run lint:secrets, npm test and npm run test:e2e pass
• docs/SPEC.md describes any behaviour this changes (its test table lists the new rule)
• User-visible changes are noted under [Unreleased] in CHANGELOG.md (none: tooling only)